Bump shelljs from 0.8.4 to 0.8.5 in /spring-boot/thymeleaf-vue/client

Bumps [shelljs](https://github.com/shelljs/shelljs) from 0.8.4 to 0.8.5.
- [Release notes](https://github.com/shelljs/shelljs/releases)
- [Changelog](https://github.com/shelljs/shelljs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/shelljs/shelljs/compare/v0.8.4...v0.8.5)

---
updated-dependencies:
- dependency-name: shelljs
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

aws/cdkv2/.mvn/wrapper/MavenWrapperDownloader.java

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2007-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import java.net.*;
+import java.io.*;
+import java.nio.channels.*;
+import java.util.Properties;
+
+public class MavenWrapperDownloader {
+
+    private static final String WRAPPER_VERSION = "0.5.6";
+    /**
+     * Default URL to download the maven-wrapper.jar from, if no 'downloadUrl' is provided.
+     */
+    private static final String DEFAULT_DOWNLOAD_URL = "https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/"
+        + WRAPPER_VERSION + "/maven-wrapper-" + WRAPPER_VERSION + ".jar";
+
+    /**
+     * Path to the maven-wrapper.properties file, which might contain a downloadUrl property to
+     * use instead of the default one.
+     */
+    private static final String MAVEN_WRAPPER_PROPERTIES_PATH =
+            ".mvn/wrapper/maven-wrapper.properties";
+
+    /**
+     * Path where the maven-wrapper.jar will be saved to.
+     */
+    private static final String MAVEN_WRAPPER_JAR_PATH =
+            ".mvn/wrapper/maven-wrapper.jar";
+
+    /**
+     * Name of the property which should be used to override the default download url for the wrapper.
+     */
+    private static final String PROPERTY_NAME_WRAPPER_URL = "wrapperUrl";
+
+    public static void main(String args[]) {
+        System.out.println("- Downloader started");
+        File baseDirectory = new File(args[0]);
+        System.out.println("- Using base directory: " + baseDirectory.getAbsolutePath());
+
+        // If the maven-wrapper.properties exists, read it and check if it contains a custom
+        // wrapperUrl parameter.
+        File mavenWrapperPropertyFile = new File(baseDirectory, MAVEN_WRAPPER_PROPERTIES_PATH);
+        String url = DEFAULT_DOWNLOAD_URL;
+        if(mavenWrapperPropertyFile.exists()) {
+            FileInputStream mavenWrapperPropertyFileInputStream = null;
+            try {
+                mavenWrapperPropertyFileInputStream = new FileInputStream(mavenWrapperPropertyFile);
+                Properties mavenWrapperProperties = new Properties();
+                mavenWrapperProperties.load(mavenWrapperPropertyFileInputStream);
+                url = mavenWrapperProperties.getProperty(PROPERTY_NAME_WRAPPER_URL, url);
+            } catch (IOException e) {
+                System.out.println("- ERROR loading '" + MAVEN_WRAPPER_PROPERTIES_PATH + "'");
+            } finally {
+                try {
+                    if(mavenWrapperPropertyFileInputStream != null) {
+                        mavenWrapperPropertyFileInputStream.close();
+                    }
+                } catch (IOException e) {
+                    // Ignore ...
+                }
+            }
+        }
+        System.out.println("- Downloading from: " + url);
+
+        File outputFile = new File(baseDirectory.getAbsolutePath(), MAVEN_WRAPPER_JAR_PATH);
+        if(!outputFile.getParentFile().exists()) {
+            if(!outputFile.getParentFile().mkdirs()) {
+                System.out.println(
+                        "- ERROR creating output directory '" + outputFile.getParentFile().getAbsolutePath() + "'");
+            }
+        }
+        System.out.println("- Downloading to: " + outputFile.getAbsolutePath());
+        try {
+            downloadFileFromURL(url, outputFile);
+            System.out.println("Done");
+            System.exit(0);
+        } catch (Throwable e) {
+            System.out.println("- Error downloading");
+            e.printStackTrace();
+            System.exit(1);
+        }
+    }
+
+    private static void downloadFileFromURL(String urlString, File destination) throws Exception {
+        if (System.getenv("MVNW_USERNAME") != null && System.getenv("MVNW_PASSWORD") != null) {
+            String username = System.getenv("MVNW_USERNAME");
+            char[] password = System.getenv("MVNW_PASSWORD").toCharArray();
+            Authenticator.setDefault(new Authenticator() {
+                @Override
+                protected PasswordAuthentication getPasswordAuthentication() {
+                    return new PasswordAuthentication(username, password);
+                }
+            });
+        }
+        URL website = new URL(urlString);
+        ReadableByteChannel rbc;
+        rbc = Channels.newChannel(website.openStream());
+        FileOutputStream fos = new FileOutputStream(destination);
+        fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
+        fos.close();
+        rbc.close();
+    }
+
+}

aws/cdkv2/.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,2 @@
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.6.3/apache-maven-3.6.3-bin.zip
+wrapperUrl=https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar

aws/cdkv2/README.md

@@ -0,0 +1,8 @@
+# Getting started with AWS CDK
+
+
+
+Blog posts about this topic:
+
+* [Getting started with AWS CDK](https://reflectoring.io/getting-started-with-aws-cdk/)
+

aws/cdkv2/cdk.context.json

@@ -0,0 +1,51 @@
+{
+  "vpc-provider:account=675153449441:filter.isDefault=true:region=us-east-1:returnAsymmetricSubnets=true": {
+    "vpcId": "vpc-e5e76998",
+    "vpcCidrBlock": "172.31.0.0/16",
+    "availabilityZones": [],
+    "subnetGroups": [
+      {
+        "name": "Public",
+        "type": "Public",
+        "subnets": [
+          {
+            "subnetId": "subnet-d71e66f6",
+            "cidr": "172.31.80.0/20",
+            "availabilityZone": "us-east-1a",
+            "routeTableId": "rtb-ed425793"
+          },
+          {
+            "subnetId": "subnet-1783815a",
+            "cidr": "172.31.16.0/20",
+            "availabilityZone": "us-east-1b",
+            "routeTableId": "rtb-ed425793"
+          },
+          {
+            "subnetId": "subnet-71d8a72e",
+            "cidr": "172.31.32.0/20",
+            "availabilityZone": "us-east-1c",
+            "routeTableId": "rtb-ed425793"
+          },
+          {
+            "subnetId": "subnet-7ee39118",
+            "cidr": "172.31.0.0/20",
+            "availabilityZone": "us-east-1d",
+            "routeTableId": "rtb-ed425793"
+          },
+          {
+            "subnetId": "subnet-a56bed94",
+            "cidr": "172.31.48.0/20",
+            "availabilityZone": "us-east-1e",
+            "routeTableId": "rtb-ed425793"
+          },
+          {
+            "subnetId": "subnet-cc1e2ac2",
+            "cidr": "172.31.64.0/20",
+            "availabilityZone": "us-east-1f",
+            "routeTableId": "rtb-ed425793"
+          }
+        ]
+      }
+    ]
+  }
+}

aws/cdkv2/cdk.json

@@ -0,0 +1,27 @@
+{
+  "app": "mvn -e -q compile exec:java",
+  "watch": {
+    "include": [
+      "**"
+    ],
+    "exclude": [
+      "README.md",
+      "cdk*.json",
+      "target",
+      "pom.xml",
+      "src/test"
+    ]
+  },
+  "context": {
+    "@aws-cdk/aws-apigateway:usagePlanKeyOrderInsensitiveId": true,
+    "@aws-cdk/core:stackRelativeExports": true,
+    "@aws-cdk/aws-rds:lowercaseDbIdentifier": true,
+    "@aws-cdk/aws-lambda:recognizeVersionProps": true,
+    "@aws-cdk/aws-cloudfront:defaultSecurityPolicyTLSv1.2_2021": true,
+    "@aws-cdk-containers/ecs-service-extensions:enableDefaultLogDriver": true,
+    "@aws-cdk/core:target-partitions": [
+      "aws",
+      "aws-cn"
+    ]
+  }
+}

aws/cdkv2/mvnw

@@ -0,0 +1,310 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# ----------------------------------------------------------------------------
+
+# ----------------------------------------------------------------------------
+# Maven Start Up Batch script
+#
+# Required ENV vars:
+# ------------------
+#   JAVA_HOME - location of a JDK home dir
+#
+# Optional ENV vars
+# -----------------
+#   M2_HOME - location of maven2's installed home dir
+#   MAVEN_OPTS - parameters passed to the Java VM when running Maven
+#     e.g. to debug Maven itself, use
+#       set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+#   MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+# ----------------------------------------------------------------------------
+
+if [ -z "$MAVEN_SKIP_RC" ] ; then
+
+  if [ -f /etc/mavenrc ] ; then
+    . /etc/mavenrc
+  fi
+
+  if [ -f "$HOME/.mavenrc" ] ; then
+    . "$HOME/.mavenrc"
+  fi
+
+fi
+
+# OS specific support.  $var _must_ be set to either true or false.
+cygwin=false;
+darwin=false;
+mingw=false
+case "`uname`" in
+  CYGWIN*) cygwin=true ;;
+  MINGW*) mingw=true;;
+  Darwin*) darwin=true
+    # Use /usr/libexec/java_home if available, otherwise fall back to /Library/Java/Home
+    # See https://developer.apple.com/library/mac/qa/qa1170/_index.html
+    if [ -z "$JAVA_HOME" ]; then
+      if [ -x "/usr/libexec/java_home" ]; then
+        export JAVA_HOME="`/usr/libexec/java_home`"
+      else
+        export JAVA_HOME="/Library/Java/Home"
+      fi
+    fi
+    ;;
+esac
+
+if [ -z "$JAVA_HOME" ] ; then
+  if [ -r /etc/gentoo-release ] ; then
+    JAVA_HOME=`java-config --jre-home`
+  fi
+fi
+
+if [ -z "$M2_HOME" ] ; then
+  ## resolve links - $0 may be a link to maven's home
+  PRG="$0"
+
+  # need this for relative symlinks
+  while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+      PRG="$link"
+    else
+      PRG="`dirname "$PRG"`/$link"
+    fi
+  done
+
+  saveddir=`pwd`
+
+  M2_HOME=`dirname "$PRG"`/..
+
+  # make it fully qualified
+  M2_HOME=`cd "$M2_HOME" && pwd`
+
+  cd "$saveddir"
+  # echo Using m2 at $M2_HOME
+fi
+
+# For Cygwin, ensure paths are in UNIX format before anything is touched
+if $cygwin ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --unix "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --unix "$CLASSPATH"`
+fi
+
+# For Mingw, ensure paths are in UNIX format before anything is touched
+if $mingw ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME="`(cd "$M2_HOME"; pwd)`"
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME="`(cd "$JAVA_HOME"; pwd)`"
+fi
+
+if [ -z "$JAVA_HOME" ]; then
+  javaExecutable="`which javac`"
+  if [ -n "$javaExecutable" ] && ! [ "`expr \"$javaExecutable\" : '\([^ ]*\)'`" = "no" ]; then
+    # readlink(1) is not available as standard on Solaris 10.
+    readLink=`which readlink`
+    if [ ! `expr "$readLink" : '\([^ ]*\)'` = "no" ]; then
+      if $darwin ; then
+        javaHome="`dirname \"$javaExecutable\"`"
+        javaExecutable="`cd \"$javaHome\" && pwd -P`/javac"
+      else
+        javaExecutable="`readlink -f \"$javaExecutable\"`"
+      fi
+      javaHome="`dirname \"$javaExecutable\"`"
+      javaHome=`expr "$javaHome" : '\(.*\)/bin'`
+      JAVA_HOME="$javaHome"
+      export JAVA_HOME
+    fi
+  fi
+fi
+
+if [ -z "$JAVACMD" ] ; then
+  if [ -n "$JAVA_HOME"  ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+      # IBM's JDK on AIX uses strange locations for the executables
+      JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+      JAVACMD="$JAVA_HOME/bin/java"
+    fi
+  else
+    JAVACMD="`which java`"
+  fi
+fi
+
+if [ ! -x "$JAVACMD" ] ; then
+  echo "Error: JAVA_HOME is not defined correctly." >&2
+  echo "  We cannot execute $JAVACMD" >&2
+  exit 1
+fi
+
+if [ -z "$JAVA_HOME" ] ; then
+  echo "Warning: JAVA_HOME environment variable is not set."
+fi
+
+CLASSWORLDS_LAUNCHER=org.codehaus.plexus.classworlds.launcher.Launcher
+
+# traverses directory structure from process work directory to filesystem root
+# first directory with .mvn subdirectory is considered project base directory
+find_maven_basedir() {
+
+  if [ -z "$1" ]
+  then
+    echo "Path not specified to find_maven_basedir"
+    return 1
+  fi
+
+  basedir="$1"
+  wdir="$1"
+  while [ "$wdir" != '/' ] ; do
+    if [ -d "$wdir"/.mvn ] ; then
+      basedir=$wdir
+      break
+    fi
+    # workaround for JBEAP-8937 (on Solaris 10/Sparc)
+    if [ -d "${wdir}" ]; then
+      wdir=`cd "$wdir/.."; pwd`
+    fi
+    # end of workaround
+  done
+  echo "${basedir}"
+}
+
+# concatenates all lines of a file
+concat_lines() {
+  if [ -f "$1" ]; then
+    echo "$(tr -s '\n' ' ' < "$1")"
+  fi
+}
+
+BASE_DIR=`find_maven_basedir "$(pwd)"`
+if [ -z "$BASE_DIR" ]; then
+  exit 1;
+fi
+
+##########################################################################################
+# Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+# This allows using the maven wrapper in projects that prohibit checking in binary data.
+##########################################################################################
+if [ -r "$BASE_DIR/.mvn/wrapper/maven-wrapper.jar" ]; then
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Found .mvn/wrapper/maven-wrapper.jar"
+    fi
+else
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Couldn't find .mvn/wrapper/maven-wrapper.jar, downloading it ..."
+    fi
+    if [ -n "$MVNW_REPOURL" ]; then
+      jarUrl="$MVNW_REPOURL/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    else
+      jarUrl="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    fi
+    while IFS="=" read key value; do
+      case "$key" in (wrapperUrl) jarUrl="$value"; break ;;
+      esac
+    done < "$BASE_DIR/.mvn/wrapper/maven-wrapper.properties"
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Downloading from: $jarUrl"
+    fi
+    wrapperJarPath="$BASE_DIR/.mvn/wrapper/maven-wrapper.jar"
+    if $cygwin; then
+      wrapperJarPath=`cygpath --path --windows "$wrapperJarPath"`
+    fi
+
+    if command -v wget > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found wget ... using wget"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            wget "$jarUrl" -O "$wrapperJarPath"
+        else
+            wget --http-user=$MVNW_USERNAME --http-password=$MVNW_PASSWORD "$jarUrl" -O "$wrapperJarPath"
+        fi
+    elif command -v curl > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found curl ... using curl"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            curl -o "$wrapperJarPath" "$jarUrl" -f
+        else
+            curl --user $MVNW_USERNAME:$MVNW_PASSWORD -o "$wrapperJarPath" "$jarUrl" -f
+        fi
+
+    else
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Falling back to using Java to download"
+        fi
+        javaClass="$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.java"
+        # For Cygwin, switch paths to Windows format before running javac
+        if $cygwin; then
+          javaClass=`cygpath --path --windows "$javaClass"`
+        fi
+        if [ -e "$javaClass" ]; then
+            if [ ! -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Compiling MavenWrapperDownloader.java ..."
+                fi
+                # Compiling the Java class
+                ("$JAVA_HOME/bin/javac" "$javaClass")
+            fi
+            if [ -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                # Running the downloader
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Running MavenWrapperDownloader.java ..."
+                fi
+                ("$JAVA_HOME/bin/java" -cp .mvn/wrapper MavenWrapperDownloader "$MAVEN_PROJECTBASEDIR")
+            fi
+        fi
+    fi
+fi
+##########################################################################################
+# End of extension
+##########################################################################################
+
+export MAVEN_PROJECTBASEDIR=${MAVEN_BASEDIR:-"$BASE_DIR"}
+if [ "$MVNW_VERBOSE" = true ]; then
+  echo $MAVEN_PROJECTBASEDIR
+fi
+MAVEN_OPTS="$(concat_lines "$MAVEN_PROJECTBASEDIR/.mvn/jvm.config") $MAVEN_OPTS"
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --path --windows "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --path --windows "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --windows "$CLASSPATH"`
+  [ -n "$MAVEN_PROJECTBASEDIR" ] &&
+    MAVEN_PROJECTBASEDIR=`cygpath --path --windows "$MAVEN_PROJECTBASEDIR"`
+fi
+
+# Provide a "standardized" way to retrieve the CLI args that will
+# work with both Windows and non-Windows executions.
+MAVEN_CMD_LINE_ARGS="$MAVEN_CONFIG $@"
+export MAVEN_CMD_LINE_ARGS
+
+WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+exec "$JAVACMD" \
+  $MAVEN_OPTS \
+  -classpath "$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.jar" \
+  "-Dmaven.home=${M2_HOME}" "-Dmaven.multiModuleProjectDirectory=${MAVEN_PROJECTBASEDIR}" \
+  ${WRAPPER_LAUNCHER} $MAVEN_CONFIG "$@"

aws/cdkv2/mvnw.cmd

@@ -0,0 +1,182 @@
+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements.  See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership.  The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License.  You may obtain a copy of the License at
+@REM
+@REM    http://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied.  See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Maven Start Up Batch script
+@REM
+@REM Required ENV vars:
+@REM JAVA_HOME - location of a JDK home dir
+@REM
+@REM Optional ENV vars
+@REM M2_HOME - location of maven2's installed home dir
+@REM MAVEN_BATCH_ECHO - set to 'on' to enable the echoing of the batch commands
+@REM MAVEN_BATCH_PAUSE - set to 'on' to wait for a keystroke before ending
+@REM MAVEN_OPTS - parameters passed to the Java VM when running Maven
+@REM     e.g. to debug Maven itself, use
+@REM set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+@REM MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+@REM ----------------------------------------------------------------------------
+
+@REM Begin all REM lines with '@' in case MAVEN_BATCH_ECHO is 'on'
+@echo off
+@REM set title of command window
+title %0
+@REM enable echoing by setting MAVEN_BATCH_ECHO to 'on'
+@if "%MAVEN_BATCH_ECHO%" == "on"  echo %MAVEN_BATCH_ECHO%
+
+@REM set %HOME% to equivalent of $HOME
+if "%HOME%" == "" (set "HOME=%HOMEDRIVE%%HOMEPATH%")
+
+@REM Execute a user defined script before this one
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPre
+@REM check for pre script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_pre.bat" call "%HOME%\mavenrc_pre.bat"
+if exist "%HOME%\mavenrc_pre.cmd" call "%HOME%\mavenrc_pre.cmd"
+:skipRcPre
+
+@setlocal
+
+set ERROR_CODE=0
+
+@REM To isolate internal variables from possible post scripts, we use another setlocal
+@setlocal
+
+@REM ==== START VALIDATION ====
+if not "%JAVA_HOME%" == "" goto OkJHome
+
+echo.
+echo Error: JAVA_HOME not found in your environment. >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+:OkJHome
+if exist "%JAVA_HOME%\bin\java.exe" goto init
+
+echo.
+echo Error: JAVA_HOME is set to an invalid directory. >&2
+echo JAVA_HOME = "%JAVA_HOME%" >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+@REM ==== END VALIDATION ====
+
+:init
+
+@REM Find the project base dir, i.e. the directory that contains the folder ".mvn".
+@REM Fallback to current working directory if not found.
+
+set MAVEN_PROJECTBASEDIR=%MAVEN_BASEDIR%
+IF NOT "%MAVEN_PROJECTBASEDIR%"=="" goto endDetectBaseDir
+
+set EXEC_DIR=%CD%
+set WDIR=%EXEC_DIR%
+:findBaseDir
+IF EXIST "%WDIR%"\.mvn goto baseDirFound
+cd ..
+IF "%WDIR%"=="%CD%" goto baseDirNotFound
+set WDIR=%CD%
+goto findBaseDir
+
+:baseDirFound
+set MAVEN_PROJECTBASEDIR=%WDIR%
+cd "%EXEC_DIR%"
+goto endDetectBaseDir
+
+:baseDirNotFound
+set MAVEN_PROJECTBASEDIR=%EXEC_DIR%
+cd "%EXEC_DIR%"
+
+:endDetectBaseDir
+
+IF NOT EXIST "%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config" goto endReadAdditionalConfig
+
+@setlocal EnableExtensions EnableDelayedExpansion
+for /F "usebackq delims=" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do set JVM_CONFIG_MAVEN_PROPS=!JVM_CONFIG_MAVEN_PROPS! %%a
+@endlocal & set JVM_CONFIG_MAVEN_PROPS=%JVM_CONFIG_MAVEN_PROPS%
+
+:endReadAdditionalConfig
+
+SET MAVEN_JAVA_EXE="%JAVA_HOME%\bin\java.exe"
+set WRAPPER_JAR="%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.jar"
+set WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+set DOWNLOAD_URL="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+
+FOR /F "tokens=1,2 delims==" %%A IN ("%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.properties") DO (
+    IF "%%A"=="wrapperUrl" SET DOWNLOAD_URL=%%B
+)
+
+@REM Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+@REM This allows using the maven wrapper in projects that prohibit checking in binary data.
+if exist %WRAPPER_JAR% (
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Found %WRAPPER_JAR%
+    )
+) else (
+    if not "%MVNW_REPOURL%" == "" (
+        SET DOWNLOAD_URL="%MVNW_REPOURL%/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    )
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Couldn't find %WRAPPER_JAR%, downloading it ...
+        echo Downloading from: %DOWNLOAD_URL%
+    )
+
+    powershell -Command "&{"^
+		"$webclient = new-object System.Net.WebClient;"^
+		"if (-not ([string]::IsNullOrEmpty('%MVNW_USERNAME%') -and [string]::IsNullOrEmpty('%MVNW_PASSWORD%'))) {"^
+		"$webclient.Credentials = new-object System.Net.NetworkCredential('%MVNW_USERNAME%', '%MVNW_PASSWORD%');"^
+		"}"^
+		"[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $webclient.DownloadFile('%DOWNLOAD_URL%', '%WRAPPER_JAR%')"^
+		"}"
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Finished downloading %WRAPPER_JAR%
+    )
+)
+@REM End of extension
+
+@REM Provide a "standardized" way to retrieve the CLI args that will
+@REM work with both Windows and non-Windows executions.
+set MAVEN_CMD_LINE_ARGS=%*
+
+%MAVEN_JAVA_EXE% %JVM_CONFIG_MAVEN_PROPS% %MAVEN_OPTS% %MAVEN_DEBUG_OPTS% -classpath %WRAPPER_JAR% "-Dmaven.multiModuleProjectDirectory=%MAVEN_PROJECTBASEDIR%" %WRAPPER_LAUNCHER% %MAVEN_CONFIG% %*
+if ERRORLEVEL 1 goto error
+goto end
+
+:error
+set ERROR_CODE=1
+
+:end
+@endlocal & set ERROR_CODE=%ERROR_CODE%
+
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPost
+@REM check for post script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_post.bat" call "%HOME%\mavenrc_post.bat"
+if exist "%HOME%\mavenrc_post.cmd" call "%HOME%\mavenrc_post.cmd"
+:skipRcPost
+
+@REM pause the script if MAVEN_BATCH_PAUSE is set to 'on'
+if "%MAVEN_BATCH_PAUSE%" == "on" pause
+
+if "%MAVEN_TERMINATE_CMD%" == "on" exit %ERROR_CODE%
+
+exit /B %ERROR_CODE%

aws/cdkv2/pom.xml

@@ -0,0 +1,61 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+         xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.myorg</groupId>
+    <artifactId>cdk-app</artifactId>
+    <version>0.1</version>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <cdk.version>2.8.0</cdk.version>
+        <constructs.version>[10.0.0,11.0.0)</constructs.version>
+        <junit.version>5.7.1</junit.version>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.8.1</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <version>3.0.0</version>
+                <configuration>
+                    <mainClass>com.myorg.CdkAppApp</mainClass>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <!-- AWS Cloud Development Kit -->
+        <dependency>
+            <groupId>software.amazon.awscdk</groupId>
+            <artifactId>aws-cdk-lib</artifactId>
+            <version>${cdk.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>software.constructs</groupId>
+            <artifactId>constructs</artifactId>
+            <version>${constructs.version}</version>
+        </dependency>
+
+        <dependency>
+          <groupId>org.junit.jupiter</groupId>
+          <artifactId>junit-jupiter</artifactId>
+          <version>${junit.version}</version>
+          <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

aws/cdkv2/src/main/java/com/myorg/CdkAppApp.java

@@ -0,0 +1,25 @@
+package com.myorg;
+
+import software.amazon.awscdk.App;
+import software.amazon.awscdk.Environment;
+import software.amazon.awscdk.StackProps;
+
+import java.util.Arrays;
+
+public class CdkAppApp {
+    public static void main(final String[] args) {
+        App app = new App();
+
+        new CdkAppStack(app, "CdkAppStack", StackProps.builder()
+         
+                .env(Environment.builder()
+                        .account("**********")
+                        .region("us-east-1")
+                        .build())
+                
+                .build());
+
+        app.synth();
+    }
+}
+

aws/cdkv2/src/main/java/com/myorg/CdkAppStack.java

@@ -0,0 +1,63 @@
+package com.myorg;
+
+import java.util.List;
+
+import org.jetbrains.annotations.NotNull;
+
+import software.amazon.awscdk.Stack;
+import software.amazon.awscdk.StackProps;
+import software.amazon.awscdk.services.ec2.BlockDeviceVolume;
+import software.amazon.awscdk.services.ec2.BlockDevice;
+import software.amazon.awscdk.services.ec2.IMachineImage;
+import software.amazon.awscdk.services.ec2.IVpc;
+import software.amazon.awscdk.services.ec2.Instance;
+import software.amazon.awscdk.services.ec2.InstanceClass;
+import software.amazon.awscdk.services.ec2.InstanceSize;
+import software.amazon.awscdk.services.ec2.InstanceType;
+import software.amazon.awscdk.services.ec2.MachineImage;
+import software.amazon.awscdk.services.ec2.SecurityGroup;
+import software.amazon.awscdk.services.ec2.Vpc;
+import software.amazon.awscdk.services.ec2.VpcLookupOptions;
+import software.constructs.Construct;
+// import software.amazon.awscdk.Duration;
+// import software.amazon.awscdk.services.sqs.Queue;
+
+public class CdkAppStack extends Stack {
+    public CdkAppStack(final Construct scope, final String id) {
+        this(scope, id, null);
+    }
+
+    public CdkAppStack(final Construct scope, final String id, final StackProps props) {
+        super(scope, id, props);
+        
+        
+		
+        VpcLookupOptions options = VpcLookupOptions.builder().isDefault(true).build();
+		IVpc vpc = Vpc.fromLookup(this, "vpc", options);
+       
+        
+        SecurityGroup securityGroup = SecurityGroup
+        		.Builder
+        		.create(this, "sg")
+        		.vpc(vpc)
+        		.allowAllOutbound(true)
+        		.build();
+        
+        
+
+        Instance.Builder.create(this, "Instance")
+		        .vpc(vpc)
+		        .instanceType(InstanceType.of(InstanceClass.BURSTABLE2, InstanceSize.MICRO))
+		        .machineImage(MachineImage.latestAmazonLinux())
+		        .blockDevices(List.of(BlockDevice.builder()
+		                .deviceName("/dev/sda1")
+		                .volume(BlockDeviceVolume.ebs(50))
+		                .build(), BlockDevice.builder()
+		                .deviceName("/dev/sdm")
+		                .volume(BlockDeviceVolume.ebs(100))
+		                .build()))
+		        .securityGroup(securityGroup)
+		        .build();
+        
+    }
+}

aws/cdkv2/src/main/java/com/myorg/MyStorageBucket.java

@@ -0,0 +1,34 @@
+/**
+ * 
+ */
+package com.myorg;
+
+
+
+import software.amazon.awscdk.Duration;
+import software.amazon.awscdk.services.s3.Bucket;
+import software.amazon.awscdk.services.s3.LifecycleRule;
+import software.constructs.Construct;
+
+/**
+ * @author pratikdas
+ *
+ */
+public class MyStorageBucket extends Construct{
+
+	public MyStorageBucket(final Construct scope, final String id) {
+		super(scope, id);
+		Bucket bucket = new Bucket(this, "mybucket");
+		
+		LifecycleRule lifecycleRule = LifecycleRule.builder()
+		         .abortIncompleteMultipartUploadAfter(Duration.minutes(30))
+		         .enabled(false)
+		         .expiration(Duration.minutes(30))
+		         .expiredObjectDeleteMarker(false)
+		         .id("id").build();
+		
+		bucket.addLifecycleRule(lifecycleRule);
+		
+	}
+
+}

aws/cdkv2/src/test/java/com/myorg/CdkAppTest.java

@@ -0,0 +1,26 @@
+// package com.myorg;
+
+// import software.amazon.awscdk.App;
+// import software.amazon.awscdk.assertions.Template;
+// import java.io.IOException;
+
+// import java.util.HashMap;
+
+// import org.junit.jupiter.api.Test;
+
+// example test. To run these tests, uncomment this file, along with the
+// example resource in java/src/main/java/com/myorg/CdkAppStack.java
+// public class CdkAppTest {
+
+//     @Test
+//     public void testStack() throws IOException {
+//         App app = new App();
+//         CdkAppStack stack = new CdkAppStack(app, "test");
+
+//         Template template = Template.fromStack(stack);
+
+//         template.hasResourceProperties("AWS::SQS::Queue", new HashMap<String, Number>() {{
+//           put("VisibilityTimeout", 300);
+//         }});
+//     }
+// }

build-all.sh

@@ -86,6 +86,11 @@ if [[ "$MODULE" == "module6" ]]
 then
   # ADD NEW MODULES HERE
   # (add new modules above the rest so you get quicker feedback if it fails)
+  build_maven_module "spring-boot/spring-boot-null-safe-annotations"
+  build maven_module "aws/cdkv2"
+  build_maven_module "immutables"
+  build maven_module "core-java/collectionops"
+  build maven_module "spring-boot/resttemplate"
   build_maven_module "spring-cloud/tracing"
   build_maven_module "core-java/versions"
   build maven_module "java-hashes"
@@ -104,7 +109,7 @@ then
   build_maven_module "logging/spring-boot"
   build_maven_module "logging/logback"
   build_maven_module "logging/log4j"
-
+  
   echo ""
   echo "+++"
   echo "+++ MODULE 6 SUCCESSFUL"

core-java/collectionops/.mvn/wrapper/MavenWrapperDownloader.java

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2007-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import java.net.*;
+import java.io.*;
+import java.nio.channels.*;
+import java.util.Properties;
+
+public class MavenWrapperDownloader {
+
+    private static final String WRAPPER_VERSION = "0.5.6";
+    /**
+     * Default URL to download the maven-wrapper.jar from, if no 'downloadUrl' is provided.
+     */
+    private static final String DEFAULT_DOWNLOAD_URL = "https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/"
+        + WRAPPER_VERSION + "/maven-wrapper-" + WRAPPER_VERSION + ".jar";
+
+    /**
+     * Path to the maven-wrapper.properties file, which might contain a downloadUrl property to
+     * use instead of the default one.
+     */
+    private static final String MAVEN_WRAPPER_PROPERTIES_PATH =
+            ".mvn/wrapper/maven-wrapper.properties";
+
+    /**
+     * Path where the maven-wrapper.jar will be saved to.
+     */
+    private static final String MAVEN_WRAPPER_JAR_PATH =
+            ".mvn/wrapper/maven-wrapper.jar";
+
+    /**
+     * Name of the property which should be used to override the default download url for the wrapper.
+     */
+    private static final String PROPERTY_NAME_WRAPPER_URL = "wrapperUrl";
+
+    public static void main(String args[]) {
+        System.out.println("- Downloader started");
+        File baseDirectory = new File(args[0]);
+        System.out.println("- Using base directory: " + baseDirectory.getAbsolutePath());
+
+        // If the maven-wrapper.properties exists, read it and check if it contains a custom
+        // wrapperUrl parameter.
+        File mavenWrapperPropertyFile = new File(baseDirectory, MAVEN_WRAPPER_PROPERTIES_PATH);
+        String url = DEFAULT_DOWNLOAD_URL;
+        if(mavenWrapperPropertyFile.exists()) {
+            FileInputStream mavenWrapperPropertyFileInputStream = null;
+            try {
+                mavenWrapperPropertyFileInputStream = new FileInputStream(mavenWrapperPropertyFile);
+                Properties mavenWrapperProperties = new Properties();
+                mavenWrapperProperties.load(mavenWrapperPropertyFileInputStream);
+                url = mavenWrapperProperties.getProperty(PROPERTY_NAME_WRAPPER_URL, url);
+            } catch (IOException e) {
+                System.out.println("- ERROR loading '" + MAVEN_WRAPPER_PROPERTIES_PATH + "'");
+            } finally {
+                try {
+                    if(mavenWrapperPropertyFileInputStream != null) {
+                        mavenWrapperPropertyFileInputStream.close();
+                    }
+                } catch (IOException e) {
+                    // Ignore ...
+                }
+            }
+        }
+        System.out.println("- Downloading from: " + url);
+
+        File outputFile = new File(baseDirectory.getAbsolutePath(), MAVEN_WRAPPER_JAR_PATH);
+        if(!outputFile.getParentFile().exists()) {
+            if(!outputFile.getParentFile().mkdirs()) {
+                System.out.println(
+                        "- ERROR creating output directory '" + outputFile.getParentFile().getAbsolutePath() + "'");
+            }
+        }
+        System.out.println("- Downloading to: " + outputFile.getAbsolutePath());
+        try {
+            downloadFileFromURL(url, outputFile);
+            System.out.println("Done");
+            System.exit(0);
+        } catch (Throwable e) {
+            System.out.println("- Error downloading");
+            e.printStackTrace();
+            System.exit(1);
+        }
+    }
+
+    private static void downloadFileFromURL(String urlString, File destination) throws Exception {
+        if (System.getenv("MVNW_USERNAME") != null && System.getenv("MVNW_PASSWORD") != null) {
+            String username = System.getenv("MVNW_USERNAME");
+            char[] password = System.getenv("MVNW_PASSWORD").toCharArray();
+            Authenticator.setDefault(new Authenticator() {
+                @Override
+                protected PasswordAuthentication getPasswordAuthentication() {
+                    return new PasswordAuthentication(username, password);
+                }
+            });
+        }
+        URL website = new URL(urlString);
+        ReadableByteChannel rbc;
+        rbc = Channels.newChannel(website.openStream());
+        FileOutputStream fos = new FileOutputStream(destination);
+        fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
+        fos.close();
+        rbc.close();
+    }
+
+}

core-java/collectionops/.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,2 @@
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.6.3/apache-maven-3.6.3-bin.zip
+wrapperUrl=https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar

core-java/collectionops/README.md

@@ -0,0 +1,3 @@
+# Related Blog Posts
+
+* [Logical Operations Between Java Collections](https://reflectoring.io/logical-ops-on-java-collections/)

core-java/collectionops/mvnw

@@ -0,0 +1,310 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# ----------------------------------------------------------------------------
+
+# ----------------------------------------------------------------------------
+# Maven Start Up Batch script
+#
+# Required ENV vars:
+# ------------------
+#   JAVA_HOME - location of a JDK home dir
+#
+# Optional ENV vars
+# -----------------
+#   M2_HOME - location of maven2's installed home dir
+#   MAVEN_OPTS - parameters passed to the Java VM when running Maven
+#     e.g. to debug Maven itself, use
+#       set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+#   MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+# ----------------------------------------------------------------------------
+
+if [ -z "$MAVEN_SKIP_RC" ] ; then
+
+  if [ -f /etc/mavenrc ] ; then
+    . /etc/mavenrc
+  fi
+
+  if [ -f "$HOME/.mavenrc" ] ; then
+    . "$HOME/.mavenrc"
+  fi
+
+fi
+
+# OS specific support.  $var _must_ be set to either true or false.
+cygwin=false;
+darwin=false;
+mingw=false
+case "`uname`" in
+  CYGWIN*) cygwin=true ;;
+  MINGW*) mingw=true;;
+  Darwin*) darwin=true
+    # Use /usr/libexec/java_home if available, otherwise fall back to /Library/Java/Home
+    # See https://developer.apple.com/library/mac/qa/qa1170/_index.html
+    if [ -z "$JAVA_HOME" ]; then
+      if [ -x "/usr/libexec/java_home" ]; then
+        export JAVA_HOME="`/usr/libexec/java_home`"
+      else
+        export JAVA_HOME="/Library/Java/Home"
+      fi
+    fi
+    ;;
+esac
+
+if [ -z "$JAVA_HOME" ] ; then
+  if [ -r /etc/gentoo-release ] ; then
+    JAVA_HOME=`java-config --jre-home`
+  fi
+fi
+
+if [ -z "$M2_HOME" ] ; then
+  ## resolve links - $0 may be a link to maven's home
+  PRG="$0"
+
+  # need this for relative symlinks
+  while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+      PRG="$link"
+    else
+      PRG="`dirname "$PRG"`/$link"
+    fi
+  done
+
+  saveddir=`pwd`
+
+  M2_HOME=`dirname "$PRG"`/..
+
+  # make it fully qualified
+  M2_HOME=`cd "$M2_HOME" && pwd`
+
+  cd "$saveddir"
+  # echo Using m2 at $M2_HOME
+fi
+
+# For Cygwin, ensure paths are in UNIX format before anything is touched
+if $cygwin ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --unix "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --unix "$CLASSPATH"`
+fi
+
+# For Mingw, ensure paths are in UNIX format before anything is touched
+if $mingw ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME="`(cd "$M2_HOME"; pwd)`"
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME="`(cd "$JAVA_HOME"; pwd)`"
+fi
+
+if [ -z "$JAVA_HOME" ]; then
+  javaExecutable="`which javac`"
+  if [ -n "$javaExecutable" ] && ! [ "`expr \"$javaExecutable\" : '\([^ ]*\)'`" = "no" ]; then
+    # readlink(1) is not available as standard on Solaris 10.
+    readLink=`which readlink`
+    if [ ! `expr "$readLink" : '\([^ ]*\)'` = "no" ]; then
+      if $darwin ; then
+        javaHome="`dirname \"$javaExecutable\"`"
+        javaExecutable="`cd \"$javaHome\" && pwd -P`/javac"
+      else
+        javaExecutable="`readlink -f \"$javaExecutable\"`"
+      fi
+      javaHome="`dirname \"$javaExecutable\"`"
+      javaHome=`expr "$javaHome" : '\(.*\)/bin'`
+      JAVA_HOME="$javaHome"
+      export JAVA_HOME
+    fi
+  fi
+fi
+
+if [ -z "$JAVACMD" ] ; then
+  if [ -n "$JAVA_HOME"  ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+      # IBM's JDK on AIX uses strange locations for the executables
+      JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+      JAVACMD="$JAVA_HOME/bin/java"
+    fi
+  else
+    JAVACMD="`which java`"
+  fi
+fi
+
+if [ ! -x "$JAVACMD" ] ; then
+  echo "Error: JAVA_HOME is not defined correctly." >&2
+  echo "  We cannot execute $JAVACMD" >&2
+  exit 1
+fi
+
+if [ -z "$JAVA_HOME" ] ; then
+  echo "Warning: JAVA_HOME environment variable is not set."
+fi
+
+CLASSWORLDS_LAUNCHER=org.codehaus.plexus.classworlds.launcher.Launcher
+
+# traverses directory structure from process work directory to filesystem root
+# first directory with .mvn subdirectory is considered project base directory
+find_maven_basedir() {
+
+  if [ -z "$1" ]
+  then
+    echo "Path not specified to find_maven_basedir"
+    return 1
+  fi
+
+  basedir="$1"
+  wdir="$1"
+  while [ "$wdir" != '/' ] ; do
+    if [ -d "$wdir"/.mvn ] ; then
+      basedir=$wdir
+      break
+    fi
+    # workaround for JBEAP-8937 (on Solaris 10/Sparc)
+    if [ -d "${wdir}" ]; then
+      wdir=`cd "$wdir/.."; pwd`
+    fi
+    # end of workaround
+  done
+  echo "${basedir}"
+}
+
+# concatenates all lines of a file
+concat_lines() {
+  if [ -f "$1" ]; then
+    echo "$(tr -s '\n' ' ' < "$1")"
+  fi
+}
+
+BASE_DIR=`find_maven_basedir "$(pwd)"`
+if [ -z "$BASE_DIR" ]; then
+  exit 1;
+fi
+
+##########################################################################################
+# Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+# This allows using the maven wrapper in projects that prohibit checking in binary data.
+##########################################################################################
+if [ -r "$BASE_DIR/.mvn/wrapper/maven-wrapper.jar" ]; then
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Found .mvn/wrapper/maven-wrapper.jar"
+    fi
+else
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Couldn't find .mvn/wrapper/maven-wrapper.jar, downloading it ..."
+    fi
+    if [ -n "$MVNW_REPOURL" ]; then
+      jarUrl="$MVNW_REPOURL/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    else
+      jarUrl="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    fi
+    while IFS="=" read key value; do
+      case "$key" in (wrapperUrl) jarUrl="$value"; break ;;
+      esac
+    done < "$BASE_DIR/.mvn/wrapper/maven-wrapper.properties"
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Downloading from: $jarUrl"
+    fi
+    wrapperJarPath="$BASE_DIR/.mvn/wrapper/maven-wrapper.jar"
+    if $cygwin; then
+      wrapperJarPath=`cygpath --path --windows "$wrapperJarPath"`
+    fi
+
+    if command -v wget > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found wget ... using wget"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            wget "$jarUrl" -O "$wrapperJarPath"
+        else
+            wget --http-user=$MVNW_USERNAME --http-password=$MVNW_PASSWORD "$jarUrl" -O "$wrapperJarPath"
+        fi
+    elif command -v curl > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found curl ... using curl"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            curl -o "$wrapperJarPath" "$jarUrl" -f
+        else
+            curl --user $MVNW_USERNAME:$MVNW_PASSWORD -o "$wrapperJarPath" "$jarUrl" -f
+        fi
+
+    else
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Falling back to using Java to download"
+        fi
+        javaClass="$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.java"
+        # For Cygwin, switch paths to Windows format before running javac
+        if $cygwin; then
+          javaClass=`cygpath --path --windows "$javaClass"`
+        fi
+        if [ -e "$javaClass" ]; then
+            if [ ! -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Compiling MavenWrapperDownloader.java ..."
+                fi
+                # Compiling the Java class
+                ("$JAVA_HOME/bin/javac" "$javaClass")
+            fi
+            if [ -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                # Running the downloader
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Running MavenWrapperDownloader.java ..."
+                fi
+                ("$JAVA_HOME/bin/java" -cp .mvn/wrapper MavenWrapperDownloader "$MAVEN_PROJECTBASEDIR")
+            fi
+        fi
+    fi
+fi
+##########################################################################################
+# End of extension
+##########################################################################################
+
+export MAVEN_PROJECTBASEDIR=${MAVEN_BASEDIR:-"$BASE_DIR"}
+if [ "$MVNW_VERBOSE" = true ]; then
+  echo $MAVEN_PROJECTBASEDIR
+fi
+MAVEN_OPTS="$(concat_lines "$MAVEN_PROJECTBASEDIR/.mvn/jvm.config") $MAVEN_OPTS"
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --path --windows "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --path --windows "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --windows "$CLASSPATH"`
+  [ -n "$MAVEN_PROJECTBASEDIR" ] &&
+    MAVEN_PROJECTBASEDIR=`cygpath --path --windows "$MAVEN_PROJECTBASEDIR"`
+fi
+
+# Provide a "standardized" way to retrieve the CLI args that will
+# work with both Windows and non-Windows executions.
+MAVEN_CMD_LINE_ARGS="$MAVEN_CONFIG $@"
+export MAVEN_CMD_LINE_ARGS
+
+WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+exec "$JAVACMD" \
+  $MAVEN_OPTS \
+  -classpath "$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.jar" \
+  "-Dmaven.home=${M2_HOME}" "-Dmaven.multiModuleProjectDirectory=${MAVEN_PROJECTBASEDIR}" \
+  ${WRAPPER_LAUNCHER} $MAVEN_CONFIG "$@"

core-java/collectionops/mvnw.cmd

@@ -0,0 +1,182 @@
+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements.  See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership.  The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License.  You may obtain a copy of the License at
+@REM
+@REM    http://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied.  See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Maven Start Up Batch script
+@REM
+@REM Required ENV vars:
+@REM JAVA_HOME - location of a JDK home dir
+@REM
+@REM Optional ENV vars
+@REM M2_HOME - location of maven2's installed home dir
+@REM MAVEN_BATCH_ECHO - set to 'on' to enable the echoing of the batch commands
+@REM MAVEN_BATCH_PAUSE - set to 'on' to wait for a keystroke before ending
+@REM MAVEN_OPTS - parameters passed to the Java VM when running Maven
+@REM     e.g. to debug Maven itself, use
+@REM set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+@REM MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+@REM ----------------------------------------------------------------------------
+
+@REM Begin all REM lines with '@' in case MAVEN_BATCH_ECHO is 'on'
+@echo off
+@REM set title of command window
+title %0
+@REM enable echoing by setting MAVEN_BATCH_ECHO to 'on'
+@if "%MAVEN_BATCH_ECHO%" == "on"  echo %MAVEN_BATCH_ECHO%
+
+@REM set %HOME% to equivalent of $HOME
+if "%HOME%" == "" (set "HOME=%HOMEDRIVE%%HOMEPATH%")
+
+@REM Execute a user defined script before this one
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPre
+@REM check for pre script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_pre.bat" call "%HOME%\mavenrc_pre.bat"
+if exist "%HOME%\mavenrc_pre.cmd" call "%HOME%\mavenrc_pre.cmd"
+:skipRcPre
+
+@setlocal
+
+set ERROR_CODE=0
+
+@REM To isolate internal variables from possible post scripts, we use another setlocal
+@setlocal
+
+@REM ==== START VALIDATION ====
+if not "%JAVA_HOME%" == "" goto OkJHome
+
+echo.
+echo Error: JAVA_HOME not found in your environment. >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+:OkJHome
+if exist "%JAVA_HOME%\bin\java.exe" goto init
+
+echo.
+echo Error: JAVA_HOME is set to an invalid directory. >&2
+echo JAVA_HOME = "%JAVA_HOME%" >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+@REM ==== END VALIDATION ====
+
+:init
+
+@REM Find the project base dir, i.e. the directory that contains the folder ".mvn".
+@REM Fallback to current working directory if not found.
+
+set MAVEN_PROJECTBASEDIR=%MAVEN_BASEDIR%
+IF NOT "%MAVEN_PROJECTBASEDIR%"=="" goto endDetectBaseDir
+
+set EXEC_DIR=%CD%
+set WDIR=%EXEC_DIR%
+:findBaseDir
+IF EXIST "%WDIR%"\.mvn goto baseDirFound
+cd ..
+IF "%WDIR%"=="%CD%" goto baseDirNotFound
+set WDIR=%CD%
+goto findBaseDir
+
+:baseDirFound
+set MAVEN_PROJECTBASEDIR=%WDIR%
+cd "%EXEC_DIR%"
+goto endDetectBaseDir
+
+:baseDirNotFound
+set MAVEN_PROJECTBASEDIR=%EXEC_DIR%
+cd "%EXEC_DIR%"
+
+:endDetectBaseDir
+
+IF NOT EXIST "%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config" goto endReadAdditionalConfig
+
+@setlocal EnableExtensions EnableDelayedExpansion
+for /F "usebackq delims=" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do set JVM_CONFIG_MAVEN_PROPS=!JVM_CONFIG_MAVEN_PROPS! %%a
+@endlocal & set JVM_CONFIG_MAVEN_PROPS=%JVM_CONFIG_MAVEN_PROPS%
+
+:endReadAdditionalConfig
+
+SET MAVEN_JAVA_EXE="%JAVA_HOME%\bin\java.exe"
+set WRAPPER_JAR="%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.jar"
+set WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+set DOWNLOAD_URL="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+
+FOR /F "tokens=1,2 delims==" %%A IN ("%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.properties") DO (
+    IF "%%A"=="wrapperUrl" SET DOWNLOAD_URL=%%B
+)
+
+@REM Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+@REM This allows using the maven wrapper in projects that prohibit checking in binary data.
+if exist %WRAPPER_JAR% (
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Found %WRAPPER_JAR%
+    )
+) else (
+    if not "%MVNW_REPOURL%" == "" (
+        SET DOWNLOAD_URL="%MVNW_REPOURL%/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    )
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Couldn't find %WRAPPER_JAR%, downloading it ...
+        echo Downloading from: %DOWNLOAD_URL%
+    )
+
+    powershell -Command "&{"^
+		"$webclient = new-object System.Net.WebClient;"^
+		"if (-not ([string]::IsNullOrEmpty('%MVNW_USERNAME%') -and [string]::IsNullOrEmpty('%MVNW_PASSWORD%'))) {"^
+		"$webclient.Credentials = new-object System.Net.NetworkCredential('%MVNW_USERNAME%', '%MVNW_PASSWORD%');"^
+		"}"^
+		"[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $webclient.DownloadFile('%DOWNLOAD_URL%', '%WRAPPER_JAR%')"^
+		"}"
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Finished downloading %WRAPPER_JAR%
+    )
+)
+@REM End of extension
+
+@REM Provide a "standardized" way to retrieve the CLI args that will
+@REM work with both Windows and non-Windows executions.
+set MAVEN_CMD_LINE_ARGS=%*
+
+%MAVEN_JAVA_EXE% %JVM_CONFIG_MAVEN_PROPS% %MAVEN_OPTS% %MAVEN_DEBUG_OPTS% -classpath %WRAPPER_JAR% "-Dmaven.multiModuleProjectDirectory=%MAVEN_PROJECTBASEDIR%" %WRAPPER_LAUNCHER% %MAVEN_CONFIG% %*
+if ERRORLEVEL 1 goto error
+goto end
+
+:error
+set ERROR_CODE=1
+
+:end
+@endlocal & set ERROR_CODE=%ERROR_CODE%
+
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPost
+@REM check for post script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_post.bat" call "%HOME%\mavenrc_post.bat"
+if exist "%HOME%\mavenrc_post.cmd" call "%HOME%\mavenrc_post.cmd"
+:skipRcPost
+
+@REM pause the script if MAVEN_BATCH_PAUSE is set to 'on'
+if "%MAVEN_BATCH_PAUSE%" == "on" pause
+
+if "%MAVEN_TERMINATE_CMD%" == "on" exit %ERROR_CODE%
+
+exit /B %ERROR_CODE%

core-java/collectionops/pom.xml

@@ -0,0 +1,24 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>io.pratik</groupId>
+	<artifactId>logicalops</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+
+	<dependencies>
+		<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-collections4 -->
+		<dependency>
+			<groupId>org.apache.commons</groupId>
+			<artifactId>commons-collections4</artifactId>
+			<version>4.4</version>
+		</dependency>
+		<dependency>
+		    <groupId>com.google.guava</groupId>
+		    <artifactId>guava</artifactId>
+		    <version>31.0.1-jre</version>
+		</dependency>
+
+
+	</dependencies>
+</project>

core-java/collectionops/src/main/java/io/pratik/CollectionHelper.java

@@ -0,0 +1,135 @@
+/**
+ * 
+ */
+package io.pratik;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
+import com.google.common.collect.Lists;
+
+/**
+ * @author pratikdas
+ *
+ */
+public class CollectionHelper {
+	
+	public <T> List<T>[] split(List<T> listToSplit){
+	    // determine the endpoints to use in `list.subList()` method
+	    int[] endpoints = {0, (listToSplit.size() + 1)/2, listToSplit.size()};
+	 
+	    
+	    List<List<T>> sublists =
+	            IntStream.rangeClosed(0, 1)
+	                    .mapToObj(i -> listToSplit.subList(endpoints[i], endpoints[i + 1]))
+	                    .collect(Collectors.toList());
+	 
+	    // return an array containing both lists
+	    return new List[] {sublists.get(0), sublists.get(1)};
+	}
+	
+	public List<Integer> add(final List<Integer> collA, final List<Integer> collB){
+
+		return Stream.concat(collA.stream(), 
+				collB.stream())
+		.collect(Collectors.toList());
+		
+		
+	}	
+	
+	public List<Integer> addWithFilter(final List<Integer> collA, final List<Integer> collB){
+
+		return Stream.concat(collA.stream(), 
+				collB.stream())
+				.filter(element -> element > 2 )
+		.collect(Collectors.toList());
+	}	
+	
+	public List<Integer> union(final List<Integer> collA, final List<Integer> collB){
+		Set<Integer> set = new LinkedHashSet<>();
+		set.addAll(collA);
+		set.addAll(collB);
+		
+		return new ArrayList<>(set);
+		
+	}
+	
+	public List<Integer> intersection(final List<Integer> collA, final List<Integer> collB){
+		List<Integer> intersectElements = collA.stream()
+				.filter(collB :: contains)
+				.collect(Collectors.toList());
+		
+		if(!intersectElements.isEmpty()) {
+			return intersectElements;
+		}else {
+			return Collections.emptyList();
+		}
+		
+	}
+	
+	public Collection<List<Integer>> partition(final List<Integer> collA, final int chunkSize){
+		final AtomicInteger counter = new AtomicInteger();
+
+		final Collection<List<Integer>> result = collA.stream()
+		    .collect(Collectors.groupingBy(it -> counter.getAndIncrement() / chunkSize))
+		    .values();
+
+		return result;
+		
+	}
+	
+
+	public List<Integer> removeDuplicates(final List<Integer> collA){
+      List<Integer> listWithoutDuplicates = new ArrayList<>(
+         new LinkedHashSet<>(collA));
+      
+      return listWithoutDuplicates;
+	}
+	
+	public List<Integer> xor(final List<Integer> collA, final List<Integer> collB){
+	      
+	      List<Integer> listOfAnotInB = collA.stream().filter(element->{
+	    	  return !collB.contains(element);
+	      }).collect(Collectors.toList());
+	      
+	      List<Integer> listOfBnotInA = collB.stream().filter(element->{
+	    	  return !collA.contains(element);
+	      }).collect(Collectors.toList());
+	      
+	      return Stream.concat(listOfAnotInB.stream(), 
+	    		  listOfBnotInA.stream())
+	    			.collect(Collectors.toList());
+	}
+	
+	public List<Integer> not(final List<Integer> collA, final List<Integer> collB){
+		  
+		  List<Integer> notList = collA.stream().filter(element->{
+	    	  return !collB.contains(element);
+	      }).collect(Collectors.toList());
+	      
+	      return notList;
+	}
+	
+	public List<Integer> subtract(final List<Integer> collA, final List<Integer> collB){
+		List<Integer> intersectElements = intersection(collA,collB);
+		
+		List<Integer> subtractedElements = collA.stream().filter(element->!intersectElements.contains(element)).collect(Collectors.toList());
+		
+		if(!subtractedElements.isEmpty()) {
+			return subtractedElements;
+		}else {
+			return Collections.emptyList();
+		}
+		
+	}
+
+}

core-java/collectionops/src/test/java/io/pratik/tests/CollectionHelperTest.java

@@ -0,0 +1,178 @@
+/**
+ * 
+ */
+package io.pratik.tests;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import io.pratik.CollectionHelper;
+
+/**
+ * @author pratikdas
+ *
+ */
+class CollectionHelperTest {
+	
+	private CollectionHelper collectionHelper;
+
+	/**
+	 * @throws java.lang.Exception
+	 */
+	@BeforeEach
+	void setUp() throws Exception {
+		collectionHelper = new CollectionHelper();
+	}
+
+	/**
+	 * @throws java.lang.Exception
+	 */
+	@AfterEach
+	void tearDown() throws Exception {
+	}
+
+	@Test
+	void testUnion() {
+		List<Integer> union = collectionHelper.union(
+				List.of(9, 8, 5, 4, 7), 
+				List.of(1, 3, 99, 4, 7));
+		
+		
+		Assertions.assertArrayEquals(
+				List.of(9, 8, 5, 4, 7, 1, 3, 99).toArray(), 
+				union.toArray());
+		
+	}
+	
+	@Test
+	void testIntersection() {
+		List<Integer> intersection = collectionHelper.intersection(
+				List.of(9,8,5,4,7, 15, 15), 
+				List.of(1,3,99,4,7));
+		
+		Assertions.assertArrayEquals(
+				List.of(4,7).toArray(), 
+				intersection.toArray());
+	}
+	
+	@Test
+	void testXOR() {
+		List<Integer> xorList = collectionHelper.xor(
+				List.of(9, 8,  5, 4, 7), 
+				List.of(1, 99, 4, 7));
+		
+		Assertions.assertArrayEquals(
+				List.of(9, 8, 5, 1, 99).toArray(), 
+				xorList.toArray());
+	}
+	
+	@Test
+	void testNOT() {
+		List<Integer> xorList = collectionHelper.not(
+				List.of(9,8,5,4,7), 
+				List.of(1,99,4,7));
+		
+		Assertions.assertArrayEquals(
+				List.of(9,8,5).toArray(), 
+				xorList.toArray());
+	}
+	
+	@Test
+	void testAddition() {
+		List<Integer> sub = collectionHelper.add(
+				List.of(9,8,5,4), 
+				List.of(1,3,99,4,7));
+		
+		
+		Assertions.assertArrayEquals(
+				List.of(9,8,5,4,1,3,99,4,7).toArray(), 
+				sub.toArray());
+	}
+	
+	@Test
+	void testAdditionWithFilter() {
+		List<Integer> list = collectionHelper.addWithFilter(
+				List.of(9,8,5,4), 
+				List.of(1,3,99,4,7));
+		
+		
+		Assertions.assertArrayEquals(
+				List.of(9,8,5,4,3,99,4,7).toArray(), 
+				list.toArray());
+	}
+
+	
+	@Test
+	void testSubtraction() {
+		List<Integer> sub = collectionHelper.subtract(
+				List.of(9,8,5,4,7, 15, 15), 
+				List.of(1,3,99,4,7));
+		
+		
+		Assertions.assertArrayEquals(
+				List.of(9,8,5,15,15).toArray(), 
+				sub.toArray());
+	}
+	
+	@Test
+	void testPartition() {
+		Collection<List<Integer>> partitions = collectionHelper.partition(
+				List.of(9, 8, 5, 4, 7, 15, 15), 2);
+		
+		Iterator<List<Integer>> iter = partitions.iterator();
+		
+		int loop = 0;
+		while(iter.hasNext()) {
+			List<Integer> element = iter.next();
+			System.out.println(element);
+			if(loop == 0)
+			   assertArrayEquals(List.of(9, 8).toArray(),element.toArray());
+			else if(loop == 1)
+				   assertArrayEquals(List.of(5, 4).toArray(),element.toArray());
+			else if(loop == 2)
+				   assertArrayEquals(List.of(7, 15).toArray(),element.toArray());
+			else if(loop == 3)
+				   assertArrayEquals(List.of(15).toArray(),element.toArray());
+		
+			++loop;
+		}
+		
+	
+	}
+	
+	@Test
+	void testRemoveDuplicates() {
+		List<Integer> uniqueElements = collectionHelper.removeDuplicates(
+				List.of(9, 8, 5, 4, 4, 7, 15, 15));
+		
+		
+		
+		Assertions.assertArrayEquals(
+				List.of(9, 8, 5, 4, 7, 15).toArray(), 
+				uniqueElements.toArray());
+	}
+	
+	@Test
+	void testSplit() {
+		List<Integer>[] subLists = collectionHelper.split(
+				List.of(9, 8, 5, 4, 7, 15, 15));
+		
+		
+		Assertions.assertArrayEquals(
+				List.of(9,8,5,4).toArray(), 
+				subLists[0].toArray());
+		
+		Assertions.assertArrayEquals(
+				List.of(7,15,15).toArray(), 
+				subLists[1].toArray());
+	}
+
+}

immutables/.gitignore

@@ -0,0 +1,33 @@
+HELP.md
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/

immutables/.mvn/wrapper/MavenWrapperDownloader.java

@@ -0,0 +1,118 @@
+/*
+ * Copyright 2007-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.net.*;
+import java.io.*;
+import java.nio.channels.*;
+import java.util.Properties;
+
+public class MavenWrapperDownloader {
+
+    private static final String WRAPPER_VERSION = "0.5.6";
+    /**
+     * Default URL to download the maven-wrapper.jar from, if no 'downloadUrl' is provided.
+     */
+    private static final String DEFAULT_DOWNLOAD_URL = "https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/"
+            + WRAPPER_VERSION + "/maven-wrapper-" + WRAPPER_VERSION + ".jar";
+
+    /**
+     * Path to the maven-wrapper.properties file, which might contain a downloadUrl property to
+     * use instead of the default one.
+     */
+    private static final String MAVEN_WRAPPER_PROPERTIES_PATH =
+            ".mvn/wrapper/maven-wrapper.properties";
+
+    /**
+     * Path where the maven-wrapper.jar will be saved to.
+     */
+    private static final String MAVEN_WRAPPER_JAR_PATH =
+            ".mvn/wrapper/maven-wrapper.jar";
+
+    /**
+     * Name of the property which should be used to override the default download url for the wrapper.
+     */
+    private static final String PROPERTY_NAME_WRAPPER_URL = "wrapperUrl";
+
+    public static void main(String args[]) {
+        System.out.println("- Downloader started");
+        File baseDirectory = new File(args[0]);
+        System.out.println("- Using base directory: " + baseDirectory.getAbsolutePath());
+
+        // If the maven-wrapper.properties exists, read it and check if it contains a custom
+        // wrapperUrl parameter.
+        File mavenWrapperPropertyFile = new File(baseDirectory, MAVEN_WRAPPER_PROPERTIES_PATH);
+        String url = DEFAULT_DOWNLOAD_URL;
+        if (mavenWrapperPropertyFile.exists()) {
+            FileInputStream mavenWrapperPropertyFileInputStream = null;
+            try {
+                mavenWrapperPropertyFileInputStream = new FileInputStream(mavenWrapperPropertyFile);
+                Properties mavenWrapperProperties = new Properties();
+                mavenWrapperProperties.load(mavenWrapperPropertyFileInputStream);
+                url = mavenWrapperProperties.getProperty(PROPERTY_NAME_WRAPPER_URL, url);
+            } catch (IOException e) {
+                System.out.println("- ERROR loading '" + MAVEN_WRAPPER_PROPERTIES_PATH + "'");
+            } finally {
+                try {
+                    if (mavenWrapperPropertyFileInputStream != null) {
+                        mavenWrapperPropertyFileInputStream.close();
+                    }
+                } catch (IOException e) {
+                    // Ignore ...
+                }
+            }
+        }
+        System.out.println("- Downloading from: " + url);
+
+        File outputFile = new File(baseDirectory.getAbsolutePath(), MAVEN_WRAPPER_JAR_PATH);
+        if (!outputFile.getParentFile().exists()) {
+            if (!outputFile.getParentFile().mkdirs()) {
+                System.out.println(
+                        "- ERROR creating output directory '" + outputFile.getParentFile().getAbsolutePath() + "'");
+            }
+        }
+        System.out.println("- Downloading to: " + outputFile.getAbsolutePath());
+        try {
+            downloadFileFromURL(url, outputFile);
+            System.out.println("Done");
+            System.exit(0);
+        } catch (Throwable e) {
+            System.out.println("- Error downloading");
+            e.printStackTrace();
+            System.exit(1);
+        }
+    }
+
+    private static void downloadFileFromURL(String urlString, File destination) throws Exception {
+        if (System.getenv("MVNW_USERNAME") != null && System.getenv("MVNW_PASSWORD") != null) {
+            String username = System.getenv("MVNW_USERNAME");
+            char[] password = System.getenv("MVNW_PASSWORD").toCharArray();
+            Authenticator.setDefault(new Authenticator() {
+                @Override
+                protected PasswordAuthentication getPasswordAuthentication() {
+                    return new PasswordAuthentication(username, password);
+                }
+            });
+        }
+        URL website = new URL(urlString);
+        ReadableByteChannel rbc;
+        rbc = Channels.newChannel(website.openStream());
+        FileOutputStream fos = new FileOutputStream(destination);
+        fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
+        fos.close();
+        rbc.close();
+    }
+
+}

immutables/.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,2 @@
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.3/apache-maven-3.8.3-bin.zip
+wrapperUrl=https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar

immutables/mvnw

@@ -0,0 +1,310 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#    https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# ----------------------------------------------------------------------------
+
+# ----------------------------------------------------------------------------
+# Maven Start Up Batch script
+#
+# Required ENV vars:
+# ------------------
+#   JAVA_HOME - location of a JDK home dir
+#
+# Optional ENV vars
+# -----------------
+#   M2_HOME - location of maven2's installed home dir
+#   MAVEN_OPTS - parameters passed to the Java VM when running Maven
+#     e.g. to debug Maven itself, use
+#       set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+#   MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+# ----------------------------------------------------------------------------
+
+if [ -z "$MAVEN_SKIP_RC" ] ; then
+
+  if [ -f /etc/mavenrc ] ; then
+    . /etc/mavenrc
+  fi
+
+  if [ -f "$HOME/.mavenrc" ] ; then
+    . "$HOME/.mavenrc"
+  fi
+
+fi
+
+# OS specific support.  $var _must_ be set to either true or false.
+cygwin=false;
+darwin=false;
+mingw=false
+case "`uname`" in
+  CYGWIN*) cygwin=true ;;
+  MINGW*) mingw=true;;
+  Darwin*) darwin=true
+    # Use /usr/libexec/java_home if available, otherwise fall back to /Library/Java/Home
+    # See https://developer.apple.com/library/mac/qa/qa1170/_index.html
+    if [ -z "$JAVA_HOME" ]; then
+      if [ -x "/usr/libexec/java_home" ]; then
+        export JAVA_HOME="`/usr/libexec/java_home`"
+      else
+        export JAVA_HOME="/Library/Java/Home"
+      fi
+    fi
+    ;;
+esac
+
+if [ -z "$JAVA_HOME" ] ; then
+  if [ -r /etc/gentoo-release ] ; then
+    JAVA_HOME=`java-config --jre-home`
+  fi
+fi
+
+if [ -z "$M2_HOME" ] ; then
+  ## resolve links - $0 may be a link to maven's home
+  PRG="$0"
+
+  # need this for relative symlinks
+  while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+      PRG="$link"
+    else
+      PRG="`dirname "$PRG"`/$link"
+    fi
+  done
+
+  saveddir=`pwd`
+
+  M2_HOME=`dirname "$PRG"`/..
+
+  # make it fully qualified
+  M2_HOME=`cd "$M2_HOME" && pwd`
+
+  cd "$saveddir"
+  # echo Using m2 at $M2_HOME
+fi
+
+# For Cygwin, ensure paths are in UNIX format before anything is touched
+if $cygwin ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --unix "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --unix "$CLASSPATH"`
+fi
+
+# For Mingw, ensure paths are in UNIX format before anything is touched
+if $mingw ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME="`(cd "$M2_HOME"; pwd)`"
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME="`(cd "$JAVA_HOME"; pwd)`"
+fi
+
+if [ -z "$JAVA_HOME" ]; then
+  javaExecutable="`which javac`"
+  if [ -n "$javaExecutable" ] && ! [ "`expr \"$javaExecutable\" : '\([^ ]*\)'`" = "no" ]; then
+    # readlink(1) is not available as standard on Solaris 10.
+    readLink=`which readlink`
+    if [ ! `expr "$readLink" : '\([^ ]*\)'` = "no" ]; then
+      if $darwin ; then
+        javaHome="`dirname \"$javaExecutable\"`"
+        javaExecutable="`cd \"$javaHome\" && pwd -P`/javac"
+      else
+        javaExecutable="`readlink -f \"$javaExecutable\"`"
+      fi
+      javaHome="`dirname \"$javaExecutable\"`"
+      javaHome=`expr "$javaHome" : '\(.*\)/bin'`
+      JAVA_HOME="$javaHome"
+      export JAVA_HOME
+    fi
+  fi
+fi
+
+if [ -z "$JAVACMD" ] ; then
+  if [ -n "$JAVA_HOME"  ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+      # IBM's JDK on AIX uses strange locations for the executables
+      JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+      JAVACMD="$JAVA_HOME/bin/java"
+    fi
+  else
+    JAVACMD="`which java`"
+  fi
+fi
+
+if [ ! -x "$JAVACMD" ] ; then
+  echo "Error: JAVA_HOME is not defined correctly." >&2
+  echo "  We cannot execute $JAVACMD" >&2
+  exit 1
+fi
+
+if [ -z "$JAVA_HOME" ] ; then
+  echo "Warning: JAVA_HOME environment variable is not set."
+fi
+
+CLASSWORLDS_LAUNCHER=org.codehaus.plexus.classworlds.launcher.Launcher
+
+# traverses directory structure from process work directory to filesystem root
+# first directory with .mvn subdirectory is considered project base directory
+find_maven_basedir() {
+
+  if [ -z "$1" ]
+  then
+    echo "Path not specified to find_maven_basedir"
+    return 1
+  fi
+
+  basedir="$1"
+  wdir="$1"
+  while [ "$wdir" != '/' ] ; do
+    if [ -d "$wdir"/.mvn ] ; then
+      basedir=$wdir
+      break
+    fi
+    # workaround for JBEAP-8937 (on Solaris 10/Sparc)
+    if [ -d "${wdir}" ]; then
+      wdir=`cd "$wdir/.."; pwd`
+    fi
+    # end of workaround
+  done
+  echo "${basedir}"
+}
+
+# concatenates all lines of a file
+concat_lines() {
+  if [ -f "$1" ]; then
+    echo "$(tr -s '\n' ' ' < "$1")"
+  fi
+}
+
+BASE_DIR=`find_maven_basedir "$(pwd)"`
+if [ -z "$BASE_DIR" ]; then
+  exit 1;
+fi
+
+##########################################################################################
+# Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+# This allows using the maven wrapper in projects that prohibit checking in binary data.
+##########################################################################################
+if [ -r "$BASE_DIR/.mvn/wrapper/maven-wrapper.jar" ]; then
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Found .mvn/wrapper/maven-wrapper.jar"
+    fi
+else
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Couldn't find .mvn/wrapper/maven-wrapper.jar, downloading it ..."
+    fi
+    if [ -n "$MVNW_REPOURL" ]; then
+      jarUrl="$MVNW_REPOURL/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    else
+      jarUrl="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    fi
+    while IFS="=" read key value; do
+      case "$key" in (wrapperUrl) jarUrl="$value"; break ;;
+      esac
+    done < "$BASE_DIR/.mvn/wrapper/maven-wrapper.properties"
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Downloading from: $jarUrl"
+    fi
+    wrapperJarPath="$BASE_DIR/.mvn/wrapper/maven-wrapper.jar"
+    if $cygwin; then
+      wrapperJarPath=`cygpath --path --windows "$wrapperJarPath"`
+    fi
+
+    if command -v wget > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found wget ... using wget"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            wget "$jarUrl" -O "$wrapperJarPath"
+        else
+            wget --http-user=$MVNW_USERNAME --http-password=$MVNW_PASSWORD "$jarUrl" -O "$wrapperJarPath"
+        fi
+    elif command -v curl > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found curl ... using curl"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            curl -o "$wrapperJarPath" "$jarUrl" -f
+        else
+            curl --user $MVNW_USERNAME:$MVNW_PASSWORD -o "$wrapperJarPath" "$jarUrl" -f
+        fi
+
+    else
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Falling back to using Java to download"
+        fi
+        javaClass="$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.java"
+        # For Cygwin, switch paths to Windows format before running javac
+        if $cygwin; then
+          javaClass=`cygpath --path --windows "$javaClass"`
+        fi
+        if [ -e "$javaClass" ]; then
+            if [ ! -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Compiling MavenWrapperDownloader.java ..."
+                fi
+                # Compiling the Java class
+                ("$JAVA_HOME/bin/javac" "$javaClass")
+            fi
+            if [ -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                # Running the downloader
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Running MavenWrapperDownloader.java ..."
+                fi
+                ("$JAVA_HOME/bin/java" -cp .mvn/wrapper MavenWrapperDownloader "$MAVEN_PROJECTBASEDIR")
+            fi
+        fi
+    fi
+fi
+##########################################################################################
+# End of extension
+##########################################################################################
+
+export MAVEN_PROJECTBASEDIR=${MAVEN_BASEDIR:-"$BASE_DIR"}
+if [ "$MVNW_VERBOSE" = true ]; then
+  echo $MAVEN_PROJECTBASEDIR
+fi
+MAVEN_OPTS="$(concat_lines "$MAVEN_PROJECTBASEDIR/.mvn/jvm.config") $MAVEN_OPTS"
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --path --windows "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --path --windows "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --windows "$CLASSPATH"`
+  [ -n "$MAVEN_PROJECTBASEDIR" ] &&
+    MAVEN_PROJECTBASEDIR=`cygpath --path --windows "$MAVEN_PROJECTBASEDIR"`
+fi
+
+# Provide a "standardized" way to retrieve the CLI args that will
+# work with both Windows and non-Windows executions.
+MAVEN_CMD_LINE_ARGS="$MAVEN_CONFIG $@"
+export MAVEN_CMD_LINE_ARGS
+
+WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+exec "$JAVACMD" \
+  $MAVEN_OPTS \
+  -classpath "$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.jar" \
+  "-Dmaven.home=${M2_HOME}" "-Dmaven.multiModuleProjectDirectory=${MAVEN_PROJECTBASEDIR}" \
+  ${WRAPPER_LAUNCHER} $MAVEN_CONFIG "$@"

immutables/mvnw.cmd

@@ -0,0 +1,182 @@
+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements.  See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership.  The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License.  You may obtain a copy of the License at
+@REM
+@REM    https://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied.  See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Maven Start Up Batch script
+@REM
+@REM Required ENV vars:
+@REM JAVA_HOME - location of a JDK home dir
+@REM
+@REM Optional ENV vars
+@REM M2_HOME - location of maven2's installed home dir
+@REM MAVEN_BATCH_ECHO - set to 'on' to enable the echoing of the batch commands
+@REM MAVEN_BATCH_PAUSE - set to 'on' to wait for a keystroke before ending
+@REM MAVEN_OPTS - parameters passed to the Java VM when running Maven
+@REM     e.g. to debug Maven itself, use
+@REM set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+@REM MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+@REM ----------------------------------------------------------------------------
+
+@REM Begin all REM lines with '@' in case MAVEN_BATCH_ECHO is 'on'
+@echo off
+@REM set title of command window
+title %0
+@REM enable echoing by setting MAVEN_BATCH_ECHO to 'on'
+@if "%MAVEN_BATCH_ECHO%" == "on"  echo %MAVEN_BATCH_ECHO%
+
+@REM set %HOME% to equivalent of $HOME
+if "%HOME%" == "" (set "HOME=%HOMEDRIVE%%HOMEPATH%")
+
+@REM Execute a user defined script before this one
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPre
+@REM check for pre script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_pre.bat" call "%HOME%\mavenrc_pre.bat"
+if exist "%HOME%\mavenrc_pre.cmd" call "%HOME%\mavenrc_pre.cmd"
+:skipRcPre
+
+@setlocal
+
+set ERROR_CODE=0
+
+@REM To isolate internal variables from possible post scripts, we use another setlocal
+@setlocal
+
+@REM ==== START VALIDATION ====
+if not "%JAVA_HOME%" == "" goto OkJHome
+
+echo.
+echo Error: JAVA_HOME not found in your environment. >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+:OkJHome
+if exist "%JAVA_HOME%\bin\java.exe" goto init
+
+echo.
+echo Error: JAVA_HOME is set to an invalid directory. >&2
+echo JAVA_HOME = "%JAVA_HOME%" >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+@REM ==== END VALIDATION ====
+
+:init
+
+@REM Find the project base dir, i.e. the directory that contains the folder ".mvn".
+@REM Fallback to current working directory if not found.
+
+set MAVEN_PROJECTBASEDIR=%MAVEN_BASEDIR%
+IF NOT "%MAVEN_PROJECTBASEDIR%"=="" goto endDetectBaseDir
+
+set EXEC_DIR=%CD%
+set WDIR=%EXEC_DIR%
+:findBaseDir
+IF EXIST "%WDIR%"\.mvn goto baseDirFound
+cd ..
+IF "%WDIR%"=="%CD%" goto baseDirNotFound
+set WDIR=%CD%
+goto findBaseDir
+
+:baseDirFound
+set MAVEN_PROJECTBASEDIR=%WDIR%
+cd "%EXEC_DIR%"
+goto endDetectBaseDir
+
+:baseDirNotFound
+set MAVEN_PROJECTBASEDIR=%EXEC_DIR%
+cd "%EXEC_DIR%"
+
+:endDetectBaseDir
+
+IF NOT EXIST "%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config" goto endReadAdditionalConfig
+
+@setlocal EnableExtensions EnableDelayedExpansion
+for /F "usebackq delims=" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do set JVM_CONFIG_MAVEN_PROPS=!JVM_CONFIG_MAVEN_PROPS! %%a
+@endlocal & set JVM_CONFIG_MAVEN_PROPS=%JVM_CONFIG_MAVEN_PROPS%
+
+:endReadAdditionalConfig
+
+SET MAVEN_JAVA_EXE="%JAVA_HOME%\bin\java.exe"
+set WRAPPER_JAR="%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.jar"
+set WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+set DOWNLOAD_URL="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+
+FOR /F "tokens=1,2 delims==" %%A IN ("%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.properties") DO (
+    IF "%%A"=="wrapperUrl" SET DOWNLOAD_URL=%%B
+)
+
+@REM Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+@REM This allows using the maven wrapper in projects that prohibit checking in binary data.
+if exist %WRAPPER_JAR% (
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Found %WRAPPER_JAR%
+    )
+) else (
+    if not "%MVNW_REPOURL%" == "" (
+        SET DOWNLOAD_URL="%MVNW_REPOURL%/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    )
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Couldn't find %WRAPPER_JAR%, downloading it ...
+        echo Downloading from: %DOWNLOAD_URL%
+    )
+
+    powershell -Command "&{"^
+		"$webclient = new-object System.Net.WebClient;"^
+		"if (-not ([string]::IsNullOrEmpty('%MVNW_USERNAME%') -and [string]::IsNullOrEmpty('%MVNW_PASSWORD%'))) {"^
+		"$webclient.Credentials = new-object System.Net.NetworkCredential('%MVNW_USERNAME%', '%MVNW_PASSWORD%');"^
+		"}"^
+		"[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $webclient.DownloadFile('%DOWNLOAD_URL%', '%WRAPPER_JAR%')"^
+		"}"
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Finished downloading %WRAPPER_JAR%
+    )
+)
+@REM End of extension
+
+@REM Provide a "standardized" way to retrieve the CLI args that will
+@REM work with both Windows and non-Windows executions.
+set MAVEN_CMD_LINE_ARGS=%*
+
+%MAVEN_JAVA_EXE% %JVM_CONFIG_MAVEN_PROPS% %MAVEN_OPTS% %MAVEN_DEBUG_OPTS% -classpath %WRAPPER_JAR% "-Dmaven.multiModuleProjectDirectory=%MAVEN_PROJECTBASEDIR%" %WRAPPER_LAUNCHER% %MAVEN_CONFIG% %*
+if ERRORLEVEL 1 goto error
+goto end
+
+:error
+set ERROR_CODE=1
+
+:end
+@endlocal & set ERROR_CODE=%ERROR_CODE%
+
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPost
+@REM check for post script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_post.bat" call "%HOME%\mavenrc_post.bat"
+if exist "%HOME%\mavenrc_post.cmd" call "%HOME%\mavenrc_post.cmd"
+:skipRcPost
+
+@REM pause the script if MAVEN_BATCH_PAUSE is set to 'on'
+if "%MAVEN_BATCH_PAUSE%" == "on" pause
+
+if "%MAVEN_TERMINATE_CMD%" == "on" exit %ERROR_CODE%
+
+exit /B %ERROR_CODE%

immutables/pom.xml

@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.reflectoring.io</groupId>
+    <artifactId>immutables</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>immutables</name>
+    <description>immutables</description>
+    <properties>
+        <java.version>11</java.version>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.immutables</groupId>
+            <artifactId>value</artifactId>
+            <version>2.8.8</version>
+        </dependency>
+    </dependencies>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>11</source>
+                    <target>11</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

immutables/src/main/java/com/reflectoring/io/immutables/Role.java

@@ -0,0 +1,13 @@
+package com.reflectoring.io.immutables;
+
+public enum Role {
+    WRITER("writer"),
+    READER("reader");
+
+    public final String value;
+
+    Role(String value){
+        this.value = value;
+    }
+
+}

immutables/src/main/java/com/reflectoring/io/immutables/basic/Article.java

@@ -0,0 +1,17 @@
+package com.reflectoring.io.immutables.basic;
+
+
+import org.immutables.value.Value;
+
+
+@Value.Immutable
+public abstract class Article {
+
+    abstract long getId();
+
+    abstract String getTitle();
+
+    abstract String getContent();
+
+    abstract long getUserId();
+}

immutables/src/main/java/com/reflectoring/io/immutables/basic/ArticleService.java

@@ -0,0 +1,27 @@
+package com.reflectoring.io.immutables.basic;
+
+import java.util.List;
+
+public class ArticleService {
+
+    // Explain how to create Immutable object the simplest way possible.
+    // Show generated class and class that we created
+    public static void main(String[] args) {
+        Article article = ImmutableArticle.builder()
+                .id(0)
+                .content("Lorem ipsum dolor sit amet.")
+                .title("Lorem ipsum article!")
+                .userId(1l)
+                .build();
+
+        User user = ImmutableUser.builder()
+                .id(1l)
+                .name("Mateo")
+                .lastname("Stjepanovic")
+                .email("mateo@mock.com")
+                .password("password")
+                .articles(List.of(article))
+                .build();
+        System.out.println(user);
+    }
+}

immutables/src/main/java/com/reflectoring/io/immutables/basic/User.java

@@ -0,0 +1,23 @@
+package com.reflectoring.io.immutables.basic;
+
+
+import org.immutables.value.Value;
+
+import java.util.List;
+
+
+@Value.Immutable
+public abstract class User {
+
+    public abstract long getId();
+
+    public abstract String getName();
+
+    public abstract String getLastname();
+
+    public abstract String getEmail();
+
+    public abstract  String getPassword();
+
+    public abstract List<Article> getArticles();
+}

immutables/src/main/java/com/reflectoring/io/immutables/builders/BuildersService.java

@@ -0,0 +1,33 @@
+package com.reflectoring.io.immutables.builders;
+
+public class BuildersService {
+
+    public static void main(String[] args) {
+//        StrictBuilderArticle strictBuilderArticle =
+//                createStrictArticle();
+        StagedBuilderArticle stagedBuilderArticle = createStagedArticle();
+    }
+
+    // Show how strict builder works
+    // Show error that is provided
+    public static StrictBuilderArticle createStrictArticle(){
+        return ImmutableStrictBuilderArticle.builder()
+                .id(0)
+                .id(1)
+                .build();
+    }
+
+    // Staged article is strict implicitly
+    // Staged article does now allow calling build method if not all mandatory fields are set
+    // Downside of using staged builders
+
+    public static StagedBuilderArticle createStagedArticle(){
+        return ImmutableStagedBuilderArticle.builder()
+                .id(0)
+                .title("Lorem ipsum article!")
+                .content("Lore ipsum...")
+                .build();
+    }
+
+
+}

immutables/src/main/java/com/reflectoring/io/immutables/builders/StagedBuilderArticle.java

@@ -0,0 +1,14 @@
+package com.reflectoring.io.immutables.builders;
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+@Value.Style(stagedBuilder = true)
+abstract class StagedBuilderArticle {
+
+    abstract long getId();
+
+    abstract String getTitle();
+
+    abstract String getContent();
+}

immutables/src/main/java/com/reflectoring/io/immutables/builders/StrictBuilderArticle.java

@@ -0,0 +1,13 @@
+package com.reflectoring.io.immutables.builders;
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+@Value.Style(strictBuilder = true)
+abstract class StrictBuilderArticle {
+    abstract long getId();
+
+    abstract String getTitle();
+
+    abstract String getContent();
+}

immutables/src/main/java/com/reflectoring/io/immutables/collections/CollectionsService.java

@@ -0,0 +1,46 @@
+package com.reflectoring.io.immutables.collections;
+
+import com.reflectoring.io.immutables.basic.Article;
+import com.reflectoring.io.immutables.basic.ImmutableArticle;
+import com.reflectoring.io.immutables.basic.ImmutableUser;
+import com.reflectoring.io.immutables.basic.User;
+
+public class CollectionsService {
+
+    public static void main(String[] args) {
+
+        Article article1 = ImmutableArticle.builder()
+                .id(0l)
+                .title("Lorem ipsum!")
+                .content("Lorem ipsum")
+                .userId(1l)
+                .build();
+
+        Article article2 = ImmutableArticle.builder()
+                .id(2l)
+                .title("Lorem ipsum!")
+                .content("Lorem ipsum")
+                .userId(1l)
+                .build();
+
+        Article article3 = ImmutableArticle.builder()
+                .id(3l)
+                .title("Lorem ipsum!")
+                .content("Lorem ipsum")
+                .userId(1l)
+                .build();
+        User user = ImmutableUser.builder()
+                .id(1l)
+                .name("Mateo")
+                .lastname("Stjepanovic")
+                .email("mock@mock.com")
+                .password("mock")
+                .addArticles(article1)
+                .addArticles(article2)
+                .build();
+        System.out.println(user);
+
+        user.getArticles().add(article3);
+
+    }
+}

immutables/src/main/java/com/reflectoring/io/immutables/constructor/ConstructorArticle.java

@@ -0,0 +1,13 @@
+package com.reflectoring.io.immutables.constructor;
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+public abstract class ConstructorArticle {
+    @Value.Parameter
+    public abstract long getId();
+    @Value.Parameter
+    public abstract String getTitle();
+    @Value.Parameter
+    public abstract String getContent();
+}

immutables/src/main/java/com/reflectoring/io/immutables/constructor/ConstructorsService.java

@@ -0,0 +1,17 @@
+package com.reflectoring.io.immutables.constructor;
+
+public class ConstructorsService {
+    public static void main(String[] args) {
+
+    }
+
+    // Out of the box constructor
+    public static ConstructorArticle createConstructorArticle(){
+        return ImmutableConstructorArticle.of(0,"Lorem ipsum article!", "Lorem ipsum...");
+    }
+
+    // How to use standard new constructor
+    public static PlainPublicConstructorArticle createPlainPublicConstructorArticle(){
+        return new ImmutablePlainPublicConstructorArticle(0,"Lorem ipsum","Lorem ipsum...");
+    }
+}

immutables/src/main/java/com/reflectoring/io/immutables/constructor/PlainPublicConstructorArticle.java

@@ -0,0 +1,14 @@
+package com.reflectoring.io.immutables.constructor;
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+@Value.Style(of = "new")
+public abstract class PlainPublicConstructorArticle {
+    @Value.Parameter
+    public abstract long getId();
+    @Value.Parameter
+    public abstract String getTitle();
+    @Value.Parameter
+    public abstract String getContent();
+}

immutables/src/main/java/com/reflectoring/io/immutables/derivedAndLazy/DerivedAndLazyService.java

@@ -0,0 +1,16 @@
+package com.reflectoring.io.immutables.derivedAndLazy;
+
+public class DerivedAndLazyService {
+
+    public static void main(String[] args) {
+        DerivedArticle article = ImmutableDerivedArticle.builder()
+                .id(1l)
+                .title("Lorem ipsum")
+                .content("Lorem ipsum dolor sit amet, consectetur " +
+                        "adipiscing elit. Donec ut sem lectus. " +
+                        "Nulla dapibus eros.")
+                .build();
+
+        System.out.println(article);
+    }
+}

immutables/src/main/java/com/reflectoring/io/immutables/derivedAndLazy/DerivedArticle.java

@@ -0,0 +1,22 @@
+package com.reflectoring.io.immutables.derivedAndLazy;
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+abstract class DerivedArticle {
+
+    abstract Long getId();
+
+    abstract String getTitle();
+
+    abstract String getContent();
+
+    @Value.Derived
+    String getSummary(){
+        String summary = getContent().substring(0,
+                getContent().length()>50 ? 50 :
+                        getContent().length());
+        return summary.length() == getContent().length() ? summary
+                : summary+"...";
+    }
+}

immutables/src/main/java/com/reflectoring/io/immutables/derivedAndLazy/LazyArticle.java

@@ -0,0 +1,23 @@
+package com.reflectoring.io.immutables.derivedAndLazy;
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+abstract class LazyArticle {
+
+    abstract Long getId();
+    
+    abstract String getTitle();
+
+    abstract String getContent();
+
+    @Value.Lazy
+    String summary(){
+        String summary = getContent().substring(0,
+                getContent().length()>50 ? 50 :
+                        getContent().length());
+        return summary.length() == getContent().length() ? summary
+                : summary+"...";
+    }
+
+}

immutables/src/main/java/com/reflectoring/io/immutables/optionalAndDefault/DefaultArticle.java

@@ -0,0 +1,17 @@
+package com.reflectoring.io.immutables.optionalAndDefault;
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+abstract class DefaultArticle {
+
+    abstract Long getId();
+
+    @Value.Default
+    String getTitle(){
+        return "Default title!";
+    }
+
+    abstract String getContent();
+
+}

immutables/src/main/java/com/reflectoring/io/immutables/optionalAndDefault/DefaultArticleInterface.java

@@ -0,0 +1,17 @@
+package com.reflectoring.io.immutables.optionalAndDefault;
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+interface DefaultArticleInterface {
+
+    Long getId();
+
+    @Value.Default
+    default String getTitle(){
+        return "Default title!";
+    }
+
+    String getContent();
+
+}

immutables/src/main/java/com/reflectoring/io/immutables/optionalAndDefault/OptionalAndDefaultService.java

@@ -0,0 +1,23 @@
+package com.reflectoring.io.immutables.optionalAndDefault;
+
+public class OptionalAndDefaultService {
+
+    //Explain optional and how we can omit values
+    //Explain default and how we use it
+    public static void main(String[] args) {
+        OptionalArticle article =  ImmutableOptionalArticle.builder().build();
+        DefaultArticle defaultArticle = ImmutableDefaultArticle.builder()
+                .id(0l)
+                .content("Lorem ipsum!")
+                .build();
+
+        DefaultArticleInterface defaultArticleInterface =
+                ImmutableDefaultArticleInterface.builder()
+                        .id(0l)
+                        .content("Lorem ipsum!")
+                        .build();
+
+        System.out.println(defaultArticle);
+        System.out.println(defaultArticleInterface);
+    }
+}

immutables/src/main/java/com/reflectoring/io/immutables/optionalAndDefault/OptionalArticle.java

@@ -0,0 +1,15 @@
+package com.reflectoring.io.immutables.optionalAndDefault;
+
+import org.immutables.value.Value;
+
+import java.util.Optional;
+
+@Value.Immutable
+abstract class OptionalArticle {
+
+    abstract Optional<Long> getId();
+
+    abstract Optional<String> getTitle();
+
+    abstract Optional<String> getContent();
+}

immutables/src/main/java/com/reflectoring/io/immutables/styles/CustomStyle.java

@@ -0,0 +1,23 @@
+package com.reflectoring.io.immutables.styles;
+
+import org.immutables.value.Value;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+// How does styles work
+// Where we can put it
+// Thing to be aware of and tests of those
+
+@Target({ElementType.PACKAGE,ElementType.TYPE})
+@Retention(RetentionPolicy.CLASS)
+@Value.Style(
+        of = "new",
+        strictBuilder = true,
+        allParameters = true,
+        visibility = Value.Style.ImplementationVisibility.PUBLIC
+
+)
+public @interface CustomStyle {}

immutables/src/main/java/com/reflectoring/io/immutables/styles/StylesArticle.java

@@ -0,0 +1,13 @@
+package com.reflectoring.io.immutables.styles;
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+@CustomStyle
+abstract class StylesArticle {
+    abstract long getId();
+
+    abstract String getTitle();
+
+    abstract String getContent();
+}

immutables/src/main/java/com/reflectoring/io/immutables/withoutImmutables/ArticleWithoutImmutable.java

@@ -0,0 +1,92 @@
+package com.reflectoring.io.immutables.withoutImmutables;
+
+import java.util.Objects;
+
+public class ArticleWithoutImmutable {
+
+    private final long id;
+
+    private final String title;
+
+    private final String content;
+
+    private final long userId;
+
+    private ArticleWithoutImmutable(long id, String title,
+                                    String content, long userId) {
+        this.id = id;
+        this.title = title;
+        this.content = content;
+        this.userId = userId;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public long getUserId() {
+        return userId;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ArticleWithoutImmutable that = (ArticleWithoutImmutable) o;
+        return id == that.id && Objects.equals(title, that.title) &&
+                Objects.equals(content, that.content);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, title, content);
+    }
+
+    public static ArticleWithoutImmutableBuilder builder() {
+        return new ArticleWithoutImmutableBuilder();
+    }
+
+    public static class ArticleWithoutImmutableBuilder {
+        private long id;
+
+        private String title;
+
+        private String content;
+
+        private long userId;
+
+        public ArticleWithoutImmutableBuilder id(long id) {
+            this.id = id;
+            return this;
+        }
+
+        public ArticleWithoutImmutableBuilder title(String title) {
+            this.title = title;
+            return this;
+        }
+
+        public ArticleWithoutImmutableBuilder content(
+                String content) {
+            this.content = content;
+            return this;
+        }
+
+        public ArticleWithoutImmutableBuilder userId(Long userId) {
+            this.userId = userId;
+            return this;
+        }
+
+        public ArticleWithoutImmutable build() {
+            return new ArticleWithoutImmutable(id, title, content,
+                    userId);
+        }
+    }
+}

immutables/src/main/java/com/reflectoring/io/immutables/withoutImmutables/UserWithoutImmutable.java

@@ -0,0 +1,166 @@
+package com.reflectoring.io.immutables.withoutImmutables;
+
+
+import com.reflectoring.io.immutables.Role;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+public class UserWithoutImmutable {
+
+    private final long id;
+
+    private final String name;
+
+    private final String lastname;
+
+    private final String email;
+
+    private final String password;
+
+    private final Role role;
+
+    private List<ArticleWithoutImmutable> articles;
+
+    private UserWithoutImmutable(long id, String name,
+                                 String lastname, String email,
+                                 String password, Role role,
+                                 List<ArticleWithoutImmutable> articles) {
+        this.id = id;
+        this.name = name;
+        this.lastname = lastname;
+        this.email = email;
+        this.password = password;
+        this.role = role;
+        this.articles = new ArrayList<>(articles);
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getLastname() {
+        return lastname;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public Role getRole() {
+        return role;
+    }
+
+    public List<ArticleWithoutImmutable> getArticles() {
+        return articles;
+    }
+
+    public UserWithoutImmutable addArticle(
+            ArticleWithoutImmutable article) {
+        this.articles.add(article);
+        return this;
+    }
+
+    public UserWithoutImmutable addArticles(
+            List<ArticleWithoutImmutable> articles) {
+        this.articles.addAll(articles);
+        return this;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        UserWithoutImmutable that = (UserWithoutImmutable) o;
+        return id == that.id && email.equals(that.email) &&
+                password.equals(that.password);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, email, password);
+    }
+
+    @Override
+    public String toString() {
+        return "UserWithoutImmutable{" +
+                "id=" + id +
+                ", name='" + name + '\'' +
+                ", lastname='" + lastname + '\'' +
+                ", role= '" + role + '\'' +
+                ", email='" + email + '\'' +
+                ", password= *****'" +
+                ", articles=" + articles +
+                '}';
+    }
+
+    public static UserWithoutImmutableBuilder builder() {
+        return new UserWithoutImmutableBuilder();
+    }
+
+    public static class UserWithoutImmutableBuilder {
+        private long id;
+
+        private String name;
+
+        private String lastname;
+
+        private Role role;
+
+        private String email;
+
+        private String password;
+
+        private List<ArticleWithoutImmutable> articles;
+
+        public UserWithoutImmutableBuilder id(long id) {
+            this.id = id;
+            return this;
+        }
+
+        public UserWithoutImmutableBuilder name(String name) {
+            this.name = name;
+            return this;
+        }
+
+        public UserWithoutImmutableBuilder lastname(String lastname) {
+            this.lastname = lastname;
+            return this;
+        }
+
+        public UserWithoutImmutableBuilder role(Role role) {
+            this.role = role;
+            return this;
+        }
+
+        public UserWithoutImmutableBuilder email(String email) {
+            this.email = email;
+            return this;
+        }
+
+        public UserWithoutImmutableBuilder password(String password) {
+            this.password = password;
+            return this;
+        }
+
+        public UserWithoutImmutableBuilder articles(
+                List<ArticleWithoutImmutable> articles) {
+            this.articles = articles;
+            return this;
+        }
+
+        public UserWithoutImmutable build() {
+            return new UserWithoutImmutable(id, name, lastname, email,
+                    password, role, articles);
+        }
+    }
+}

spring-boot/feature-flags/src/main/java/io/reflectoring/featureflags/FeatureFlagService.java

@@ -1,5 +1,8 @@
 package io.reflectoring.featureflags;
 
+import java.time.LocalDateTime;
+import java.util.Optional;
+
 public interface FeatureFlagService {
 
     /**
@@ -24,4 +27,21 @@ public interface FeatureFlagService {
 
     Boolean isNewServiceEnabled();
 
+    /**
+     * Returns the current time to be used by the welcome message feature.
+     */
+    Optional<LocalDateTime> currentDateForWelcomeMessage();
+
+    /**
+     * Returns the current time to be used by the welcome email feature.
+     */
+    Optional<LocalDateTime> currentDateForWelcomeEmails();
+
+    Optional<LocalDateTime> currentDateForWelcomeMessage(String username);
+
+    /**
+     * Returns the current time to be used by the welcome email feature.
+     */
+    Optional<LocalDateTime> currentDateForWelcomeEmails(String username);
+
 }

spring-boot/feature-flags/src/main/java/io/reflectoring/featureflags/FeatureFlagsApplication.java

@@ -2,8 +2,10 @@ package io.reflectoring.featureflags;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.scheduling.annotation.EnableScheduling;
 
 @SpringBootApplication
+@EnableScheduling
 public class FeatureFlagsApplication {
 
 	public static void main(String[] args) {

spring-boot/feature-flags/src/main/java/io/reflectoring/featureflags/datebased/DateFeatureFlagController.java

@@ -0,0 +1,49 @@
+package io.reflectoring.featureflags.datebased;
+
+import io.reflectoring.featureflags.FeatureFlagService;
+import io.reflectoring.featureflags.web.UserSession;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.servlet.ModelAndView;
+
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.util.Map;
+import java.util.Optional;
+
+@Controller
+public class DateFeatureFlagController {
+
+    private final UserSession userSession;
+    private final FeatureFlagService featureFlagService;
+
+    DateFeatureFlagController(UserSession userSession, FeatureFlagService featureFlagService) {
+        this.userSession = userSession;
+        this.featureFlagService = featureFlagService;
+    }
+
+    @GetMapping(path = {"/welcome"})
+    ModelAndView welcome() {
+        userSession.login("ben");
+
+        Optional<LocalDateTime> date = featureFlagService.currentDateForWelcomeMessage();
+
+        if (date.isEmpty()) {
+            return new ModelAndView("/welcome-page-without-message.html");
+        }
+
+        LocalTime time = date.get().toLocalTime();
+        String welcomeMessage = "";
+
+        if (time.isBefore(LocalTime.NOON)) {
+            welcomeMessage = "Good Morning!";
+        } else if (time.isBefore(LocalTime.of(17, 0))) {
+            welcomeMessage = "Good Day!";
+        } else {
+            welcomeMessage = "Good Evening!";
+        }
+
+        return new ModelAndView("/welcome-page.html", Map.of("welcomeMessage", welcomeMessage));
+    }
+
+}

spring-boot/feature-flags/src/main/java/io/reflectoring/featureflags/datebased/EmailSender.java

@@ -0,0 +1,70 @@
+package io.reflectoring.featureflags.datebased;
+
+import io.reflectoring.featureflags.FeatureFlagService;
+import io.reflectoring.featureflags.web.UserSession;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Component;
+
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+
+@Component
+public class EmailSender {
+
+    private final Logger logger = LoggerFactory.getLogger(EmailSender.class);
+    private final FeatureFlagService featureFlagService;
+
+    public EmailSender(FeatureFlagService featureFlagService, UserSession userSession) {
+        this.featureFlagService = featureFlagService;
+    }
+
+    @Scheduled(fixedDelay = 10000)
+    public void sendWelcomeEmails() {
+        for (User user : getUsers()) {
+            Optional<LocalDateTime> now = featureFlagService.currentDateForWelcomeEmails(user.name);
+            if (now.isEmpty()) {
+                logger.info("not sending email to user {}", user.name);
+                continue;
+            }
+            if (user.registrationDate.isBefore(now.get().minusDays(14L).toLocalDate())) {
+                sendEmail(user, "Welcome email after 14 days");
+            } else if (user.registrationDate.isBefore(now.get().minusDays(7L).toLocalDate())) {
+                sendEmail(user, "Welcome email after 7 days");
+            } else if (user.registrationDate.isBefore(now.get().minusDays(1L).toLocalDate())) {
+                sendEmail(user, "Welcome email after 1 day");
+            }
+        }
+    }
+
+    private void sendEmail(User user, String message) {
+        logger.info("sending email to user {} with message {}", user.name, message);
+    }
+
+    private List<User> getUsers() {
+        return Arrays.asList(
+                new User("alice", LocalDate.now().minusDays(1)),
+                new User("bob", LocalDate.now().minusDays(2)),
+                new User("charlie", LocalDate.now().minusDays(3)),
+                new User("ben", LocalDate.now().minusDays(4)),
+                new User("tom", LocalDate.now().minusDays(5)),
+                new User("hugo", LocalDate.now().minusDays(6))
+        );
+    }
+
+    static class User {
+
+        private final String name;
+        private final LocalDate registrationDate;
+
+        User(String name, LocalDate registrationDate) {
+            this.name = name;
+            this.registrationDate = registrationDate;
+        }
+    }
+
+}

spring-boot/feature-flags/src/main/java/io/reflectoring/featureflags/ff4j/FF4JFeatureFlagService.java

@@ -4,6 +4,9 @@ import io.reflectoring.featureflags.FeatureFlagService;
 import org.ff4j.FF4j;
 import org.springframework.stereotype.Component;
 
+import java.time.LocalDateTime;
+import java.util.Optional;
+
 @Component("ff4j")
 public class FF4JFeatureFlagService implements FeatureFlagService {
 
@@ -38,4 +41,28 @@ public class FF4JFeatureFlagService implements FeatureFlagService {
         return null;
     }
 
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeMessage() {
+        // not supported
+        return Optional.of(LocalDateTime.now());
+    }
+
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeEmails() {
+        // not supported
+        return Optional.of(LocalDateTime.now());
+    }
+
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeMessage(String username) {
+        // not supported
+        return Optional.of(LocalDateTime.now());
+    }
+
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeEmails(String username) {
+        // not supported
+        return Optional.of(LocalDateTime.now());
+    }
+
 }

spring-boot/feature-flags/src/main/java/io/reflectoring/featureflags/launchdarkly/LaunchDarklyFeatureFlagService.java

@@ -4,17 +4,25 @@ import com.launchdarkly.sdk.LDUser;
 import com.launchdarkly.sdk.server.LDClient;
 import io.reflectoring.featureflags.FeatureFlagService;
 import io.reflectoring.featureflags.web.UserSession;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.context.annotation.Primary;
 import org.springframework.stereotype.Component;
 
 import javax.annotation.PostConstruct;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
+import java.util.Optional;
 
 @Component("launchdarkly")
 @Primary
 public class LaunchDarklyFeatureFlagService implements FeatureFlagService {
 
+    private final Logger logger = LoggerFactory.getLogger(LaunchDarklyFeatureFlagService.class);
     private final LDClient launchdarklyClient;
     private final UserSession userSession;
+    private final DateTimeFormatter dateFormatter = DateTimeFormatter.ISO_OFFSET_DATE_TIME;
 
     public LaunchDarklyFeatureFlagService(LDClient launchdarklyClient, UserSession userSession) {
         this.launchdarklyClient = launchdarklyClient;
@@ -63,9 +71,91 @@ public class LaunchDarklyFeatureFlagService implements FeatureFlagService {
         return true;
     }
 
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeMessage() {
+        String stringValue = launchdarklyClient.stringVariation("current-date-for-welcome-message", getLaunchdarklyUserFromSession(), "false");
+
+        if ("false".equals(stringValue)) {
+            return Optional.empty();
+        }
+
+        if ("now".equals(stringValue)) {
+            return Optional.of(LocalDateTime.now());
+        }
+
+        try {
+            return Optional.of(LocalDateTime.parse(stringValue, dateFormatter));
+        } catch (DateTimeParseException e) {
+            logger.warn("could not parse date ... falling back to current date", e);
+            return Optional.of(LocalDateTime.now());
+        }
+    }
+
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeEmails() {
+        String stringValue = launchdarklyClient.stringVariation("current-date-for-welcome-email", getLaunchdarklyUserFromSession(), "false");
+
+        if ("false".equals(stringValue)) {
+            return Optional.empty();
+        }
+
+        if ("now".equals(stringValue)) {
+            return Optional.of(LocalDateTime.now());
+        }
+
+        try {
+            return Optional.of(LocalDateTime.parse(stringValue, dateFormatter));
+        } catch (DateTimeParseException e) {
+            logger.warn("could not parse date ... falling back to current date", e);
+            return Optional.of(LocalDateTime.now());
+        }
+    }
+
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeMessage(String username) {
+        String stringValue = launchdarklyClient.stringVariation("current-date-for-welcome-message", new LDUser.Builder(username).build(), "false");
+
+        if ("false".equals(stringValue)) {
+            return Optional.empty();
+        }
+
+        if ("now".equals(stringValue)) {
+            return Optional.of(LocalDateTime.now());
+        }
+
+        try {
+            return Optional.of(LocalDateTime.parse(stringValue, dateFormatter));
+        } catch (DateTimeParseException e) {
+            logger.warn("could not parse date ... falling back to current date", e);
+            return Optional.of(LocalDateTime.now());
+        }
+    }
+
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeEmails(String username) {
+        String stringValue = launchdarklyClient.stringVariation("current-date-for-welcome-email", new LDUser.Builder(username).build(), "false");
+
+        if ("false".equals(stringValue)) {
+            return Optional.empty();
+        }
+
+        if ("now".equals(stringValue)) {
+            return Optional.of(LocalDateTime.now());
+        }
+
+        try {
+            return Optional.of(LocalDateTime.parse(stringValue, dateFormatter));
+        } catch (DateTimeParseException e) {
+            logger.warn("could not parse date ... falling back to current date", e);
+            return Optional.of(LocalDateTime.now());
+        }
+    }
+
     private LDUser getLaunchdarklyUserFromSession() {
         return new LDUser.Builder(userSession.getUsername())
                 .custom("clicked", userSession.hasClicked())
                 .build();
     }
+
+
 }

spring-boot/feature-flags/src/main/java/io/reflectoring/featureflags/togglz/TooglzFeatureFlagService.java

@@ -3,6 +3,9 @@ package io.reflectoring.featureflags.togglz;
 import io.reflectoring.featureflags.FeatureFlagService;
 import org.springframework.stereotype.Component;
 
+import java.time.LocalDateTime;
+import java.util.Optional;
+
 @Component("togglz")
 public class TooglzFeatureFlagService implements FeatureFlagService {
 
@@ -31,4 +34,29 @@ public class TooglzFeatureFlagService implements FeatureFlagService {
         return false;
     }
 
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeMessage() {
+        // not supported
+        return Optional.of(LocalDateTime.now());
+    }
+
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeEmails() {
+        // not supported
+        return Optional.of(LocalDateTime.now());
+    }
+
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeMessage(String username) {
+        // not supported
+        return Optional.of(LocalDateTime.now());
+    }
+
+    @Override
+    public Optional<LocalDateTime> currentDateForWelcomeEmails(String username) {
+        // not supported
+        return Optional.of(LocalDateTime.now());
+    }
+
+
 }

spring-boot/feature-flags/src/main/resources/templates/welcome-page-without-message.html

@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+
+    <title>Welcome</title>
+    <style>
+    td {
+      padding:10px;
+    }
+    </style>
+
+  </head>
+
+  <body>
+
+    This is the version of the welcome page without a welcome message.
+
+  </body>
+</html>

spring-boot/feature-flags/src/main/resources/templates/welcome-page.html

@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+
+    <title>Your features</title>
+    <style>
+    td {
+      padding:10px;
+    }
+    </style>
+
+  </head>
+
+  <body>
+
+  <h1 th:text="${welcomeMessage}"></h1>
+
+  </body>
+</html>

spring-boot/resttemplate/.mvn/wrapper/MavenWrapperDownloader.java

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2007-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import java.net.*;
+import java.io.*;
+import java.nio.channels.*;
+import java.util.Properties;
+
+public class MavenWrapperDownloader {
+
+    private static final String WRAPPER_VERSION = "0.5.6";
+    /**
+     * Default URL to download the maven-wrapper.jar from, if no 'downloadUrl' is provided.
+     */
+    private static final String DEFAULT_DOWNLOAD_URL = "https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/"
+        + WRAPPER_VERSION + "/maven-wrapper-" + WRAPPER_VERSION + ".jar";
+
+    /**
+     * Path to the maven-wrapper.properties file, which might contain a downloadUrl property to
+     * use instead of the default one.
+     */
+    private static final String MAVEN_WRAPPER_PROPERTIES_PATH =
+            ".mvn/wrapper/maven-wrapper.properties";
+
+    /**
+     * Path where the maven-wrapper.jar will be saved to.
+     */
+    private static final String MAVEN_WRAPPER_JAR_PATH =
+            ".mvn/wrapper/maven-wrapper.jar";
+
+    /**
+     * Name of the property which should be used to override the default download url for the wrapper.
+     */
+    private static final String PROPERTY_NAME_WRAPPER_URL = "wrapperUrl";
+
+    public static void main(String args[]) {
+        System.out.println("- Downloader started");
+        File baseDirectory = new File(args[0]);
+        System.out.println("- Using base directory: " + baseDirectory.getAbsolutePath());
+
+        // If the maven-wrapper.properties exists, read it and check if it contains a custom
+        // wrapperUrl parameter.
+        File mavenWrapperPropertyFile = new File(baseDirectory, MAVEN_WRAPPER_PROPERTIES_PATH);
+        String url = DEFAULT_DOWNLOAD_URL;
+        if(mavenWrapperPropertyFile.exists()) {
+            FileInputStream mavenWrapperPropertyFileInputStream = null;
+            try {
+                mavenWrapperPropertyFileInputStream = new FileInputStream(mavenWrapperPropertyFile);
+                Properties mavenWrapperProperties = new Properties();
+                mavenWrapperProperties.load(mavenWrapperPropertyFileInputStream);
+                url = mavenWrapperProperties.getProperty(PROPERTY_NAME_WRAPPER_URL, url);
+            } catch (IOException e) {
+                System.out.println("- ERROR loading '" + MAVEN_WRAPPER_PROPERTIES_PATH + "'");
+            } finally {
+                try {
+                    if(mavenWrapperPropertyFileInputStream != null) {
+                        mavenWrapperPropertyFileInputStream.close();
+                    }
+                } catch (IOException e) {
+                    // Ignore ...
+                }
+            }
+        }
+        System.out.println("- Downloading from: " + url);
+
+        File outputFile = new File(baseDirectory.getAbsolutePath(), MAVEN_WRAPPER_JAR_PATH);
+        if(!outputFile.getParentFile().exists()) {
+            if(!outputFile.getParentFile().mkdirs()) {
+                System.out.println(
+                        "- ERROR creating output directory '" + outputFile.getParentFile().getAbsolutePath() + "'");
+            }
+        }
+        System.out.println("- Downloading to: " + outputFile.getAbsolutePath());
+        try {
+            downloadFileFromURL(url, outputFile);
+            System.out.println("Done");
+            System.exit(0);
+        } catch (Throwable e) {
+            System.out.println("- Error downloading");
+            e.printStackTrace();
+            System.exit(1);
+        }
+    }
+
+    private static void downloadFileFromURL(String urlString, File destination) throws Exception {
+        if (System.getenv("MVNW_USERNAME") != null && System.getenv("MVNW_PASSWORD") != null) {
+            String username = System.getenv("MVNW_USERNAME");
+            char[] password = System.getenv("MVNW_PASSWORD").toCharArray();
+            Authenticator.setDefault(new Authenticator() {
+                @Override
+                protected PasswordAuthentication getPasswordAuthentication() {
+                    return new PasswordAuthentication(username, password);
+                }
+            });
+        }
+        URL website = new URL(urlString);
+        ReadableByteChannel rbc;
+        rbc = Channels.newChannel(website.openStream());
+        FileOutputStream fos = new FileOutputStream(destination);
+        fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
+        fos.close();
+        rbc.close();
+    }
+
+}

spring-boot/resttemplate/.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,2 @@
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.6.3/apache-maven-3.6.3-bin.zip
+wrapperUrl=https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar

spring-boot/resttemplate/README.md

@@ -0,0 +1,3 @@
+# Related Blog Posts
+
+* [Complete Guide to Spring RestTemplate](https://reflectoring.io/spring-resttemplate/)

spring-boot/resttemplate/mvnw

@@ -0,0 +1,310 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# ----------------------------------------------------------------------------
+
+# ----------------------------------------------------------------------------
+# Maven Start Up Batch script
+#
+# Required ENV vars:
+# ------------------
+#   JAVA_HOME - location of a JDK home dir
+#
+# Optional ENV vars
+# -----------------
+#   M2_HOME - location of maven2's installed home dir
+#   MAVEN_OPTS - parameters passed to the Java VM when running Maven
+#     e.g. to debug Maven itself, use
+#       set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+#   MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+# ----------------------------------------------------------------------------
+
+if [ -z "$MAVEN_SKIP_RC" ] ; then
+
+  if [ -f /etc/mavenrc ] ; then
+    . /etc/mavenrc
+  fi
+
+  if [ -f "$HOME/.mavenrc" ] ; then
+    . "$HOME/.mavenrc"
+  fi
+
+fi
+
+# OS specific support.  $var _must_ be set to either true or false.
+cygwin=false;
+darwin=false;
+mingw=false
+case "`uname`" in
+  CYGWIN*) cygwin=true ;;
+  MINGW*) mingw=true;;
+  Darwin*) darwin=true
+    # Use /usr/libexec/java_home if available, otherwise fall back to /Library/Java/Home
+    # See https://developer.apple.com/library/mac/qa/qa1170/_index.html
+    if [ -z "$JAVA_HOME" ]; then
+      if [ -x "/usr/libexec/java_home" ]; then
+        export JAVA_HOME="`/usr/libexec/java_home`"
+      else
+        export JAVA_HOME="/Library/Java/Home"
+      fi
+    fi
+    ;;
+esac
+
+if [ -z "$JAVA_HOME" ] ; then
+  if [ -r /etc/gentoo-release ] ; then
+    JAVA_HOME=`java-config --jre-home`
+  fi
+fi
+
+if [ -z "$M2_HOME" ] ; then
+  ## resolve links - $0 may be a link to maven's home
+  PRG="$0"
+
+  # need this for relative symlinks
+  while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+      PRG="$link"
+    else
+      PRG="`dirname "$PRG"`/$link"
+    fi
+  done
+
+  saveddir=`pwd`
+
+  M2_HOME=`dirname "$PRG"`/..
+
+  # make it fully qualified
+  M2_HOME=`cd "$M2_HOME" && pwd`
+
+  cd "$saveddir"
+  # echo Using m2 at $M2_HOME
+fi
+
+# For Cygwin, ensure paths are in UNIX format before anything is touched
+if $cygwin ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --unix "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --unix "$CLASSPATH"`
+fi
+
+# For Mingw, ensure paths are in UNIX format before anything is touched
+if $mingw ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME="`(cd "$M2_HOME"; pwd)`"
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME="`(cd "$JAVA_HOME"; pwd)`"
+fi
+
+if [ -z "$JAVA_HOME" ]; then
+  javaExecutable="`which javac`"
+  if [ -n "$javaExecutable" ] && ! [ "`expr \"$javaExecutable\" : '\([^ ]*\)'`" = "no" ]; then
+    # readlink(1) is not available as standard on Solaris 10.
+    readLink=`which readlink`
+    if [ ! `expr "$readLink" : '\([^ ]*\)'` = "no" ]; then
+      if $darwin ; then
+        javaHome="`dirname \"$javaExecutable\"`"
+        javaExecutable="`cd \"$javaHome\" && pwd -P`/javac"
+      else
+        javaExecutable="`readlink -f \"$javaExecutable\"`"
+      fi
+      javaHome="`dirname \"$javaExecutable\"`"
+      javaHome=`expr "$javaHome" : '\(.*\)/bin'`
+      JAVA_HOME="$javaHome"
+      export JAVA_HOME
+    fi
+  fi
+fi
+
+if [ -z "$JAVACMD" ] ; then
+  if [ -n "$JAVA_HOME"  ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+      # IBM's JDK on AIX uses strange locations for the executables
+      JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+      JAVACMD="$JAVA_HOME/bin/java"
+    fi
+  else
+    JAVACMD="`which java`"
+  fi
+fi
+
+if [ ! -x "$JAVACMD" ] ; then
+  echo "Error: JAVA_HOME is not defined correctly." >&2
+  echo "  We cannot execute $JAVACMD" >&2
+  exit 1
+fi
+
+if [ -z "$JAVA_HOME" ] ; then
+  echo "Warning: JAVA_HOME environment variable is not set."
+fi
+
+CLASSWORLDS_LAUNCHER=org.codehaus.plexus.classworlds.launcher.Launcher
+
+# traverses directory structure from process work directory to filesystem root
+# first directory with .mvn subdirectory is considered project base directory
+find_maven_basedir() {
+
+  if [ -z "$1" ]
+  then
+    echo "Path not specified to find_maven_basedir"
+    return 1
+  fi
+
+  basedir="$1"
+  wdir="$1"
+  while [ "$wdir" != '/' ] ; do
+    if [ -d "$wdir"/.mvn ] ; then
+      basedir=$wdir
+      break
+    fi
+    # workaround for JBEAP-8937 (on Solaris 10/Sparc)
+    if [ -d "${wdir}" ]; then
+      wdir=`cd "$wdir/.."; pwd`
+    fi
+    # end of workaround
+  done
+  echo "${basedir}"
+}
+
+# concatenates all lines of a file
+concat_lines() {
+  if [ -f "$1" ]; then
+    echo "$(tr -s '\n' ' ' < "$1")"
+  fi
+}
+
+BASE_DIR=`find_maven_basedir "$(pwd)"`
+if [ -z "$BASE_DIR" ]; then
+  exit 1;
+fi
+
+##########################################################################################
+# Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+# This allows using the maven wrapper in projects that prohibit checking in binary data.
+##########################################################################################
+if [ -r "$BASE_DIR/.mvn/wrapper/maven-wrapper.jar" ]; then
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Found .mvn/wrapper/maven-wrapper.jar"
+    fi
+else
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Couldn't find .mvn/wrapper/maven-wrapper.jar, downloading it ..."
+    fi
+    if [ -n "$MVNW_REPOURL" ]; then
+      jarUrl="$MVNW_REPOURL/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    else
+      jarUrl="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    fi
+    while IFS="=" read key value; do
+      case "$key" in (wrapperUrl) jarUrl="$value"; break ;;
+      esac
+    done < "$BASE_DIR/.mvn/wrapper/maven-wrapper.properties"
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Downloading from: $jarUrl"
+    fi
+    wrapperJarPath="$BASE_DIR/.mvn/wrapper/maven-wrapper.jar"
+    if $cygwin; then
+      wrapperJarPath=`cygpath --path --windows "$wrapperJarPath"`
+    fi
+
+    if command -v wget > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found wget ... using wget"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            wget "$jarUrl" -O "$wrapperJarPath"
+        else
+            wget --http-user=$MVNW_USERNAME --http-password=$MVNW_PASSWORD "$jarUrl" -O "$wrapperJarPath"
+        fi
+    elif command -v curl > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found curl ... using curl"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            curl -o "$wrapperJarPath" "$jarUrl" -f
+        else
+            curl --user $MVNW_USERNAME:$MVNW_PASSWORD -o "$wrapperJarPath" "$jarUrl" -f
+        fi
+
+    else
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Falling back to using Java to download"
+        fi
+        javaClass="$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.java"
+        # For Cygwin, switch paths to Windows format before running javac
+        if $cygwin; then
+          javaClass=`cygpath --path --windows "$javaClass"`
+        fi
+        if [ -e "$javaClass" ]; then
+            if [ ! -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Compiling MavenWrapperDownloader.java ..."
+                fi
+                # Compiling the Java class
+                ("$JAVA_HOME/bin/javac" "$javaClass")
+            fi
+            if [ -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                # Running the downloader
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Running MavenWrapperDownloader.java ..."
+                fi
+                ("$JAVA_HOME/bin/java" -cp .mvn/wrapper MavenWrapperDownloader "$MAVEN_PROJECTBASEDIR")
+            fi
+        fi
+    fi
+fi
+##########################################################################################
+# End of extension
+##########################################################################################
+
+export MAVEN_PROJECTBASEDIR=${MAVEN_BASEDIR:-"$BASE_DIR"}
+if [ "$MVNW_VERBOSE" = true ]; then
+  echo $MAVEN_PROJECTBASEDIR
+fi
+MAVEN_OPTS="$(concat_lines "$MAVEN_PROJECTBASEDIR/.mvn/jvm.config") $MAVEN_OPTS"
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --path --windows "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --path --windows "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --windows "$CLASSPATH"`
+  [ -n "$MAVEN_PROJECTBASEDIR" ] &&
+    MAVEN_PROJECTBASEDIR=`cygpath --path --windows "$MAVEN_PROJECTBASEDIR"`
+fi
+
+# Provide a "standardized" way to retrieve the CLI args that will
+# work with both Windows and non-Windows executions.
+MAVEN_CMD_LINE_ARGS="$MAVEN_CONFIG $@"
+export MAVEN_CMD_LINE_ARGS
+
+WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+exec "$JAVACMD" \
+  $MAVEN_OPTS \
+  -classpath "$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.jar" \
+  "-Dmaven.home=${M2_HOME}" "-Dmaven.multiModuleProjectDirectory=${MAVEN_PROJECTBASEDIR}" \
+  ${WRAPPER_LAUNCHER} $MAVEN_CONFIG "$@"

spring-boot/resttemplate/mvnw.cmd

@@ -0,0 +1,182 @@
+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements.  See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership.  The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License.  You may obtain a copy of the License at
+@REM
+@REM    http://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied.  See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Maven Start Up Batch script
+@REM
+@REM Required ENV vars:
+@REM JAVA_HOME - location of a JDK home dir
+@REM
+@REM Optional ENV vars
+@REM M2_HOME - location of maven2's installed home dir
+@REM MAVEN_BATCH_ECHO - set to 'on' to enable the echoing of the batch commands
+@REM MAVEN_BATCH_PAUSE - set to 'on' to wait for a keystroke before ending
+@REM MAVEN_OPTS - parameters passed to the Java VM when running Maven
+@REM     e.g. to debug Maven itself, use
+@REM set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+@REM MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+@REM ----------------------------------------------------------------------------
+
+@REM Begin all REM lines with '@' in case MAVEN_BATCH_ECHO is 'on'
+@echo off
+@REM set title of command window
+title %0
+@REM enable echoing by setting MAVEN_BATCH_ECHO to 'on'
+@if "%MAVEN_BATCH_ECHO%" == "on"  echo %MAVEN_BATCH_ECHO%
+
+@REM set %HOME% to equivalent of $HOME
+if "%HOME%" == "" (set "HOME=%HOMEDRIVE%%HOMEPATH%")
+
+@REM Execute a user defined script before this one
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPre
+@REM check for pre script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_pre.bat" call "%HOME%\mavenrc_pre.bat"
+if exist "%HOME%\mavenrc_pre.cmd" call "%HOME%\mavenrc_pre.cmd"
+:skipRcPre
+
+@setlocal
+
+set ERROR_CODE=0
+
+@REM To isolate internal variables from possible post scripts, we use another setlocal
+@setlocal
+
+@REM ==== START VALIDATION ====
+if not "%JAVA_HOME%" == "" goto OkJHome
+
+echo.
+echo Error: JAVA_HOME not found in your environment. >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+:OkJHome
+if exist "%JAVA_HOME%\bin\java.exe" goto init
+
+echo.
+echo Error: JAVA_HOME is set to an invalid directory. >&2
+echo JAVA_HOME = "%JAVA_HOME%" >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+@REM ==== END VALIDATION ====
+
+:init
+
+@REM Find the project base dir, i.e. the directory that contains the folder ".mvn".
+@REM Fallback to current working directory if not found.
+
+set MAVEN_PROJECTBASEDIR=%MAVEN_BASEDIR%
+IF NOT "%MAVEN_PROJECTBASEDIR%"=="" goto endDetectBaseDir
+
+set EXEC_DIR=%CD%
+set WDIR=%EXEC_DIR%
+:findBaseDir
+IF EXIST "%WDIR%"\.mvn goto baseDirFound
+cd ..
+IF "%WDIR%"=="%CD%" goto baseDirNotFound
+set WDIR=%CD%
+goto findBaseDir
+
+:baseDirFound
+set MAVEN_PROJECTBASEDIR=%WDIR%
+cd "%EXEC_DIR%"
+goto endDetectBaseDir
+
+:baseDirNotFound
+set MAVEN_PROJECTBASEDIR=%EXEC_DIR%
+cd "%EXEC_DIR%"
+
+:endDetectBaseDir
+
+IF NOT EXIST "%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config" goto endReadAdditionalConfig
+
+@setlocal EnableExtensions EnableDelayedExpansion
+for /F "usebackq delims=" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do set JVM_CONFIG_MAVEN_PROPS=!JVM_CONFIG_MAVEN_PROPS! %%a
+@endlocal & set JVM_CONFIG_MAVEN_PROPS=%JVM_CONFIG_MAVEN_PROPS%
+
+:endReadAdditionalConfig
+
+SET MAVEN_JAVA_EXE="%JAVA_HOME%\bin\java.exe"
+set WRAPPER_JAR="%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.jar"
+set WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+set DOWNLOAD_URL="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+
+FOR /F "tokens=1,2 delims==" %%A IN ("%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.properties") DO (
+    IF "%%A"=="wrapperUrl" SET DOWNLOAD_URL=%%B
+)
+
+@REM Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+@REM This allows using the maven wrapper in projects that prohibit checking in binary data.
+if exist %WRAPPER_JAR% (
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Found %WRAPPER_JAR%
+    )
+) else (
+    if not "%MVNW_REPOURL%" == "" (
+        SET DOWNLOAD_URL="%MVNW_REPOURL%/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    )
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Couldn't find %WRAPPER_JAR%, downloading it ...
+        echo Downloading from: %DOWNLOAD_URL%
+    )
+
+    powershell -Command "&{"^
+		"$webclient = new-object System.Net.WebClient;"^
+		"if (-not ([string]::IsNullOrEmpty('%MVNW_USERNAME%') -and [string]::IsNullOrEmpty('%MVNW_PASSWORD%'))) {"^
+		"$webclient.Credentials = new-object System.Net.NetworkCredential('%MVNW_USERNAME%', '%MVNW_PASSWORD%');"^
+		"}"^
+		"[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $webclient.DownloadFile('%DOWNLOAD_URL%', '%WRAPPER_JAR%')"^
+		"}"
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Finished downloading %WRAPPER_JAR%
+    )
+)
+@REM End of extension
+
+@REM Provide a "standardized" way to retrieve the CLI args that will
+@REM work with both Windows and non-Windows executions.
+set MAVEN_CMD_LINE_ARGS=%*
+
+%MAVEN_JAVA_EXE% %JVM_CONFIG_MAVEN_PROPS% %MAVEN_OPTS% %MAVEN_DEBUG_OPTS% -classpath %WRAPPER_JAR% "-Dmaven.multiModuleProjectDirectory=%MAVEN_PROJECTBASEDIR%" %WRAPPER_LAUNCHER% %MAVEN_CONFIG% %*
+if ERRORLEVEL 1 goto error
+goto end
+
+:error
+set ERROR_CODE=1
+
+:end
+@endlocal & set ERROR_CODE=%ERROR_CODE%
+
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPost
+@REM check for post script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_post.bat" call "%HOME%\mavenrc_post.bat"
+if exist "%HOME%\mavenrc_post.cmd" call "%HOME%\mavenrc_post.cmd"
+:skipRcPost
+
+@REM pause the script if MAVEN_BATCH_PAUSE is set to 'on'
+if "%MAVEN_BATCH_PAUSE%" == "on" pause
+
+if "%MAVEN_TERMINATE_CMD%" == "on" exit %ERROR_CODE%
+
+exit /B %ERROR_CODE%

spring-boot/resttemplate/pom.xml

@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>2.6.1</version>
+		<relativePath /> <!-- lookup parent from repository -->
+	</parent>
+	<groupId>io.pratik</groupId>
+	<artifactId>restclient</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<name>restclient</name>
+	<description>Project to demo Spring Rest Client</description>
+	<properties>
+		<java.version>11</java.version>
+		<xstream.version>1.4.11.1</xstream.version>
+	</properties>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-web</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.apache.httpcomponents</groupId>
+			<artifactId>httpclient</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-oxm</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>com.thoughtworks.xstream</groupId>
+			<artifactId>xstream</artifactId>
+			<version>${xstream.version}</version>
+		</dependency>
+
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

spring-boot/resttemplate/src/main/java/io/pratik/apis/models/Product.java

@@ -0,0 +1,68 @@
+/**
+ * 
+ */
+package io.pratik.apis.models;
+
+import java.util.UUID;
+
+/**
+ * @author pratikdas
+ *
+ */
+public class Product {
+	
+	
+	
+	public Product(String name, String brand, Double price, String sku) {
+		super();
+		id = UUID.randomUUID().toString();
+		this.name = name;
+		this.brand = brand;
+		this.price = price;
+		this.sku = sku;
+	}
+	private String id;
+	private String name;
+	private String brand;
+	private Double price;
+	private String sku;
+	public String getName() {
+		return name;
+	}
+	
+	
+	public String getId() {
+		return id;
+	}
+
+
+	public void setId(String id) {
+		this.id = id;
+	}
+
+
+	public void setName(String name) {
+		this.name = name;
+	}
+	public String getBrand() {
+		return brand;
+	}
+	public void setBrand(String brand) {
+		this.brand = brand;
+	}
+	public Double getPrice() {
+		return price;
+	}
+	public void setPrice(Double price) {
+		this.price = price;
+	}
+	public String getSku() {
+		return sku;
+	}
+	public void setSku(String sku) {
+		this.sku = sku;
+	}
+	
+	
+
+}

spring-boot/resttemplate/src/main/java/io/pratik/restclient/CustomErrorHandler.java

@@ -0,0 +1,60 @@
+/**
+ * 
+ */
+package io.pratik.restclient;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.stream.Collectors;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.client.ClientHttpResponse;
+import org.springframework.web.client.ResponseErrorHandler;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import io.pratik.restclient.models.RestTemplateError;
+
+/**
+ * @author pratikdas
+ *
+ */
+public class CustomErrorHandler implements ResponseErrorHandler{
+
+	@Override
+	public boolean hasError(ClientHttpResponse response) 
+			throws IOException {
+		return (
+		          response.getStatusCode().series() ==
+		              HttpStatus.Series.CLIENT_ERROR 
+		              
+		          || response.getStatusCode().series() == 
+		              HttpStatus.Series.SERVER_ERROR
+		       );
+		    
+	}
+
+	@Override
+	public void handleError(ClientHttpResponse response) 
+			throws IOException {
+
+	    if (response.getStatusCode().is4xxClientError() 
+	    		|| response.getStatusCode().is5xxServerError()) {
+
+
+	    	try (BufferedReader reader = new BufferedReader(new InputStreamReader(response.getBody()))) {
+	          String httpBodyResponse = reader.lines().collect(Collectors.joining(""));
+	          
+	  		  ObjectMapper mapper = new ObjectMapper();
+			  RestTemplateError restTemplateError = mapper.readValue(httpBodyResponse, RestTemplateError.class);
+
+			  
+	          throw new RestServiceException(restTemplateError.getPath(), response.getStatusCode(), restTemplateError.getError());
+	        }	
+	    
+	    }
+		
+	
+	}
+}

spring-boot/resttemplate/src/main/java/io/pratik/restclient/InventoryServiceClient.java

@@ -0,0 +1,41 @@
+/**
+ * 
+ */
+package io.pratik.restclient;
+
+import java.util.Collections;
+
+import org.springframework.boot.web.client.RestTemplateBuilder;
+import org.springframework.http.RequestEntity;
+import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
+import org.springframework.stereotype.Service;
+import org.springframework.web.client.RestTemplate;
+
+/**
+ * @author pratikdas
+ *
+ */
+@Service
+public class InventoryServiceClient {
+	
+	private RestTemplate restTemplate;
+	
+	public InventoryServiceClient(RestTemplateBuilder builder) {
+		restTemplate = builder.errorHandler(
+				new CustomErrorHandler())
+				.build();
+		
+		restTemplate.setMessageConverters(Collections.singletonList(
+		        new MappingJackson2HttpMessageConverter()));
+		
+		restTemplate = new RestTemplate(
+		        Collections.singletonList(new MappingJackson2HttpMessageConverter()));
+		
+	
+	}
+	
+	
+
+
+
+}

spring-boot/resttemplate/src/main/java/io/pratik/restclient/ProductController.java

@@ -0,0 +1,83 @@
+/**
+ * 
+ */
+package io.pratik.restclient;
+
+import java.util.List;
+import java.util.UUID;
+
+import javax.websocket.server.PathParam;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.RestController;
+
+import io.pratik.apis.models.Product;
+
+/**
+ * @author pratikdas
+ *
+ */
+@RestController
+public class ProductController {
+	
+	private List<Product> products = List.of(new Product("Television", "Samsung",1145.67,"S001"),
+		       new Product("Washing Machine", "LG",114.67,"L001"),
+		       new Product("Laptop", "Apple",11453.67,"A001"));
+	
+	
+	@GetMapping(value="/products/{id}", produces=MediaType.APPLICATION_XML_VALUE)
+	public @ResponseBody Product fetchProducts(@PathParam("id") String productId){
+		
+		return products.get(1);
+	}
+	
+	@GetMapping("/products")
+	public List<Product> fetchProducts(){
+		
+		return products;
+	}
+	
+	@PostMapping("/products")
+	public ResponseEntity<String> createProduct(@RequestBody Product product){
+		
+		// Create product with ID;
+		String productID = UUID.randomUUID().toString();
+		product.setId(productID);
+		products.add(product);
+		
+		return ResponseEntity.ok().body("{\"productID\":\""+productID+"\"}");
+	}
+
+	@PutMapping("/products")
+	public ResponseEntity<String> updateProduct(@RequestBody Product product){
+		
+		products.set(1, product);
+		// Update product. Return success or failure without response body
+		return ResponseEntity.ok().build();
+	}
+	
+	@DeleteMapping("/products")
+	public ResponseEntity<String> deleteProduct(@RequestBody Product product){
+		
+		products.remove(1);
+		// Update product. Return success or failure without response body
+		return ResponseEntity.ok().build();
+	}
+	
+	@GetMapping("/products/error")
+	public ResponseEntity<Product> fetchProductWithError(){
+		
+		return ResponseEntity.status(HttpStatus.BAD_REQUEST).build();
+	}
+	
+
+
+}

spring-boot/resttemplate/src/main/java/io/pratik/restclient/RestConsumer.java

@@ -0,0 +1,320 @@
+/**
+ * 
+ */
+package io.pratik.restclient;
+
+import java.net.URI;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+import org.springframework.boot.web.client.RestTemplateBuilder;
+import org.springframework.boot.web.client.RestTemplateCustomizer;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.http.client.ClientHttpRequestFactory;
+import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
+import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.http.converter.xml.MarshallingHttpMessageConverter;
+import org.springframework.oxm.xstream.XStreamMarshaller;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+import org.springframework.web.client.RequestCallback;
+import org.springframework.web.client.ResponseExtractor;
+import org.springframework.web.client.RestTemplate;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import io.pratik.apis.models.Product;
+
+/**
+ * @author pratikdas
+ *
+ */
+public class RestConsumer {
+	
+	public void getProductAsJson() {
+		RestTemplate restTemplate = new RestTemplate();
+		String resourceUrl
+		  = "http://localhost:8080/products";
+		ResponseEntity<String> response
+		  = restTemplate.getForEntity(resourceUrl, String.class);
+		
+		String productsJson = response.getBody();
+		
+		System.out.println(productsJson);
+	}
+	
+	public void getProducts() {
+		//RestTemplate restTemplate = new RestTemplate(getClientHttpRequestFactory());
+		RestTemplate restTemplate = new RestTemplate();
+		String resourceUrl
+		  = "http://localhost:8080/products";
+		ResponseEntity<List> response
+		  = restTemplate.getForEntity(resourceUrl, List.class);
+		
+		List<Product> products = response.getBody();
+		System.out.println(products);
+	}
+	
+	public void getProductObjects() {
+		//RestTemplate restTemplate = new RestTemplate(getClientHttpRequestFactory());
+		RestTemplate restTemplate = new RestTemplate();
+		String resourceUrl
+		  = "http://localhost:8080/products";
+		List<?> products
+		  = restTemplate.getForObject(resourceUrl, List.class);
+		
+		System.out.println(products);
+	}
+	
+	public void getHeaders() {
+		RestTemplate restTemplate = new RestTemplate();
+		String resourceUrl
+		  = "http://localhost:8080/products";
+		HttpHeaders httpHeaders = restTemplate.headForHeaders(resourceUrl);
+		System.out.println("headers "+httpHeaders);
+	}
+	
+	public void createProduct() {
+		RestTemplate restTemplate = new RestTemplate();
+		String resourceUrl
+		  = "http://localhost:8080/products";
+		HttpEntity<Product> request = new HttpEntity<Product>(new Product("Television", "Samsung",1145.67,"S001"));
+		String productCreateResponse = restTemplate.postForObject(resourceUrl, request, String.class);
+		
+		
+		
+		System.out.println(productCreateResponse);
+	}
+	
+	public void createProductWithExchange() {
+		
+		RestTemplate restTemplate = new RestTemplate();
+		String resourceUrl
+		  = "http://localhost:8080/products";
+		HttpEntity<Product> request = new HttpEntity<Product>(new Product("Television", "Samsung",1145.67,"S001"));
+		ResponseEntity<String> productCreateResponse = restTemplate.exchange(resourceUrl, HttpMethod.POST, request, String.class);
+		
+		
+		
+		System.out.println(productCreateResponse);
+	}
+	
+	public void updateProductWithExchange() {
+		RestTemplate restTemplate = new RestTemplate();
+		
+		 HttpHeaders headers = new HttpHeaders();
+		 headers.setContentType(MediaType.APPLICATION_JSON);
+		 headers.set("Authorization", "Bearer ...");
+		 
+		String resourceUrl
+		  = "http://localhost:8080/products";
+		HttpEntity<Product> request = new HttpEntity<Product>(new Product("Television", "Samsung",1145.67,"S001"));
+	    restTemplate.exchange(resourceUrl, HttpMethod.PUT, request, Void.class);
+		
+		
+	}
+	
+
+	
+	public void getProductAsStream() {
+		final Product fetchProductRequest = new Product("Television", "Samsung",1145.67,"S001");
+		RestTemplate restTemplate = new RestTemplate();
+		String resourceUrl
+		  = "http://localhost:8080/products";
+	
+		
+		RequestCallback requestCallback = request -> {
+	        ObjectMapper mapper = new ObjectMapper();
+	            mapper.writeValue(request.getBody(), 
+	            		fetchProductRequest);
+
+		        request.getHeaders()
+			     .setAccept(Arrays.asList(
+			    		 MediaType.APPLICATION_OCTET_STREAM, 
+			    		 MediaType.ALL));
+		        };
+
+		ResponseExtractor<Void> responseExtractor = response -> {
+			     Path path = Paths.get("some/path");
+			     Files.copy(response.getBody(), path);
+			     return null;
+			 };
+		restTemplate.execute(resourceUrl, 
+				HttpMethod.GET, 
+				requestCallback, 
+				responseExtractor );
+		
+		
+	}
+	
+	
+	public void submitProductForm() {
+		RestTemplate restTemplate = new RestTemplate();
+		String resourceUrl
+		  = "http://localhost:8080/products";
+		
+		HttpHeaders headers = new HttpHeaders();
+		headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
+		
+		MultiValueMap<String, String> map= new LinkedMultiValueMap<>();
+		map.add("id", "1");
+		
+		HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(map, headers);
+		
+		ResponseEntity<String> response = restTemplate.postForEntity(
+				  resourceUrl+"/form", request , String.class);
+		
+		
+		
+		
+		System.out.println(response.getBody());
+	}
+	
+	private ClientHttpRequestFactory getClientHttpRequestFactory() {
+	    int connectTimeout = 5000;
+	    int readTimeout = 5000;
+	    HttpComponentsClientHttpRequestFactory clientHttpRequestFactory
+	      = new HttpComponentsClientHttpRequestFactory();
+	    clientHttpRequestFactory.setConnectTimeout(connectTimeout);
+	    clientHttpRequestFactory.setReadTimeout(readTimeout);
+	    return clientHttpRequestFactory;
+	}
+	
+	public void createProductWithLocation() {
+		RestTemplate restTemplate = new RestTemplate(getClientHttpRequestFactory());
+		String resourceUrl
+		  = "http://localhost:8080/products";
+		HttpEntity<Product> request = new HttpEntity<Product>(new Product("Television", "Samsung",1145.67,"S001"));
+		URI location = restTemplate.postForLocation(resourceUrl, request);
+		
+		
+		
+		System.out.println(location);
+	}
+	
+	public void getAllowedOps() {
+		RestTemplate restTemplate = new RestTemplate();
+		
+		String resourceUrl
+		  = "http://localhost:8080/products";
+		Set<HttpMethod> optionsForAllow = restTemplate.optionsForAllow(resourceUrl);
+		HttpMethod[] supportedMethods
+		  = {HttpMethod.GET, HttpMethod.POST, HttpMethod.PUT, HttpMethod.DELETE};	
+		System.out.println(optionsForAllow);
+	}
+	
+	public void getProductWithError() {
+		RestTemplate restTemplate = new RestTemplate();
+		
+		RestTemplateCustomizer customizers = new RestTemplateCustomizer() {
+			
+			@Override
+			public void customize(RestTemplate restTemplate) {
+				restTemplate.setErrorHandler(new CustomErrorHandler());
+				
+				
+				
+			}
+		};
+		RestTemplateBuilder builder = new RestTemplateBuilder(customizers );
+		// restTemplate = new RestTemplate();// builder.build();
+		restTemplate =  builder.build();
+		
+		System.out.println("Default error handler::" + restTemplate.getErrorHandler());
+		String resourceUrl
+		  = "http://localhost:8080/product/error";
+		try {
+			Product product
+			  = restTemplate.getForObject(resourceUrl, Product.class);
+
+		}catch(RestServiceException ex) {
+			System.out.println("error occured: ["+ ex.getError() + "] in service:: "+ ex.getServiceName());
+		}
+	
+	}
+	
+	public void getProductWithMessageTransformer() {
+		RestTemplate restTemplate = new RestTemplate();
+		
+		RestTemplateCustomizer customizers = new RestTemplateCustomizer() {
+			
+			@Override
+			public void customize(RestTemplate restTemplate) {
+				restTemplate.setErrorHandler(new CustomErrorHandler());
+				
+			}
+		};
+		RestTemplateBuilder builder = new RestTemplateBuilder(customizers );
+		// restTemplate = new RestTemplate();// builder.build();
+		restTemplate =  builder.build();
+		
+		System.out.println("Default error handler::" + restTemplate.getErrorHandler());
+		String resourceUrl
+		  = "http://localhost:8080/product/error";
+		try {
+			Product product
+			  = restTemplate.getForObject(resourceUrl, Product.class);
+
+		}catch(RestServiceException ex) {
+			System.out.println("error occured: ["+ ex.getError() + "] in service:: "+ ex.getServiceName());
+		}
+	
+	}
+	
+	public void getProductAsXML() {
+		RestTemplate restTemplate = new RestTemplate();
+		restTemplate.setMessageConverters(getXmlMessageConverter());
+		
+		HttpHeaders headers = new HttpHeaders();
+	    headers.setAccept(Collections.singletonList(MediaType.APPLICATION_XML));
+	    HttpEntity<String> entity = new HttpEntity<>(headers);
+	    
+	    String productID = "P123445";
+
+	    String resourceUrl
+		  = "http://localhost:8080/products/"+productID;
+	    ResponseEntity<Product> response = 
+	      restTemplate.exchange(resourceUrl, HttpMethod.GET, entity, Product.class, "1");
+	    Product resource = response.getBody();
+	}
+	
+	private List<HttpMessageConverter<?>> getXmlMessageConverter() {
+	    XStreamMarshaller marshaller = new XStreamMarshaller();
+	    marshaller.setAnnotatedClasses(Product.class);
+	    MarshallingHttpMessageConverter marshallingConverter = 
+	      new MarshallingHttpMessageConverter(marshaller);
+
+	    List<HttpMessageConverter<?>> converters = new ArrayList<>();
+	    converters.add(marshallingConverter);
+	    return converters;
+	}
+	
+	
+	public static void main(String[] args) {
+		RestConsumer restConsumer = new RestConsumer();
+		
+		/*restConsumer.getProductAsJson();
+		restConsumer.getProducts();
+		restConsumer.getProductObjects();
+		
+		restConsumer.getHeaders(); restConsumer.createProduct();
+		restConsumer.getAllowedOps(); restConsumer.updateProductWithExchange();
+		restConsumer.getProductAsStream();
+		restConsumer.createProductWithLocation();
+		*/
+		//restConsumer.getProductWithError();
+		restConsumer.getProductAsXML();
+		
+	}
+
+}

spring-boot/resttemplate/src/main/java/io/pratik/restclient/RestServiceException.java

@@ -0,0 +1,39 @@
+/**
+ * 
+ */
+package io.pratik.restclient;
+
+import org.springframework.http.HttpStatus;
+
+/**
+ * @author pratikdas
+ *
+ */
+public class RestServiceException extends RuntimeException {
+
+	 
+	private static final long serialVersionUID = 1L;
+	
+	private String serviceName;
+	private HttpStatus statusCode;
+	private String error;
+	public RestServiceException(String serviceName, HttpStatus statusCode, String error) {
+		super();
+		this.serviceName = serviceName;
+		this.statusCode = statusCode;
+		this.error = error;
+	}
+	public String getServiceName() {
+		return serviceName;
+	}
+	public HttpStatus getStatusCode() {
+		return statusCode;
+	}
+	public String getError() {
+		return error;
+	}
+
+	
+
+}
+

spring-boot/resttemplate/src/main/java/io/pratik/restclient/RestclientApplication.java

@@ -0,0 +1,23 @@
+package io.pratik.restclient;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.web.client.RestTemplateBuilder;
+import org.springframework.context.annotation.Bean;
+import org.springframework.web.client.RestTemplate;
+
+@SpringBootApplication
+public class RestclientApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(RestclientApplication.class, args);
+	}
+	
+	@Bean
+	public RestTemplate restTemplate(RestTemplateBuilder builder) {
+		return builder.build();
+	}
+
+	
+
+}

spring-boot/resttemplate/src/main/java/io/pratik/restclient/models/RestTemplateError.java

@@ -0,0 +1,42 @@
+/**
+ * 
+ */
+package io.pratik.restclient.models;
+
+/**
+ * @author pratikdas
+ *
+ */
+public class RestTemplateError {
+	private String timestamp;
+	private String status;
+	private String error;
+	private String path;
+	public String getTimestamp() {
+		return timestamp;
+	}
+	public void setTimestamp(String timestamp) {
+		this.timestamp = timestamp;
+	}
+	public String getStatus() {
+		return status;
+	}
+	public void setStatus(String status) {
+		this.status = status;
+	}
+	public String getError() {
+		return error;
+	}
+	public void setError(String error) {
+		this.error = error;
+	}
+	public String getPath() {
+		return path;
+	}
+	public void setPath(String path) {
+		this.path = path;
+	}
+	
+	
+
+}

spring-boot/resttemplate/src/main/resources/application.properties

@@ -0,0 +1 @@
+

spring-boot/spring-boot-null-safe-annotations/.gitignore

@@ -0,0 +1,33 @@
+HELP.md
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/

spring-boot/spring-boot-null-safe-annotations/.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,2 @@
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.3/apache-maven-3.8.3-bin.zip
+wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar

spring-boot/spring-boot-null-safe-annotations/README.md

@@ -0,0 +1,5 @@
+# Spring Boot Null-safety Annotations
+
+This module is created to explain how developers can use the null-safety annotations (`@NonNull`, `@Nullable`, `@NonNullFields`, `@NonNullApi`) in the Spring Boot code.
+
+## [Blog post link](https://reflectoring.io/spring-boot-null-safety-annotations/)

spring-boot/spring-boot-null-safe-annotations/mvnw

@@ -0,0 +1,316 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#    https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# ----------------------------------------------------------------------------
+
+# ----------------------------------------------------------------------------
+# Maven Start Up Batch script
+#
+# Required ENV vars:
+# ------------------
+#   JAVA_HOME - location of a JDK home dir
+#
+# Optional ENV vars
+# -----------------
+#   M2_HOME - location of maven2's installed home dir
+#   MAVEN_OPTS - parameters passed to the Java VM when running Maven
+#     e.g. to debug Maven itself, use
+#       set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+#   MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+# ----------------------------------------------------------------------------
+
+if [ -z "$MAVEN_SKIP_RC" ] ; then
+
+  if [ -f /usr/local/etc/mavenrc ] ; then
+    . /usr/local/etc/mavenrc
+  fi
+
+  if [ -f /etc/mavenrc ] ; then
+    . /etc/mavenrc
+  fi
+
+  if [ -f "$HOME/.mavenrc" ] ; then
+    . "$HOME/.mavenrc"
+  fi
+
+fi
+
+# OS specific support.  $var _must_ be set to either true or false.
+cygwin=false;
+darwin=false;
+mingw=false
+case "`uname`" in
+  CYGWIN*) cygwin=true ;;
+  MINGW*) mingw=true;;
+  Darwin*) darwin=true
+    # Use /usr/libexec/java_home if available, otherwise fall back to /Library/Java/Home
+    # See https://developer.apple.com/library/mac/qa/qa1170/_index.html
+    if [ -z "$JAVA_HOME" ]; then
+      if [ -x "/usr/libexec/java_home" ]; then
+        export JAVA_HOME="`/usr/libexec/java_home`"
+      else
+        export JAVA_HOME="/Library/Java/Home"
+      fi
+    fi
+    ;;
+esac
+
+if [ -z "$JAVA_HOME" ] ; then
+  if [ -r /etc/gentoo-release ] ; then
+    JAVA_HOME=`java-config --jre-home`
+  fi
+fi
+
+if [ -z "$M2_HOME" ] ; then
+  ## resolve links - $0 may be a link to maven's home
+  PRG="$0"
+
+  # need this for relative symlinks
+  while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+      PRG="$link"
+    else
+      PRG="`dirname "$PRG"`/$link"
+    fi
+  done
+
+  saveddir=`pwd`
+
+  M2_HOME=`dirname "$PRG"`/..
+
+  # make it fully qualified
+  M2_HOME=`cd "$M2_HOME" && pwd`
+
+  cd "$saveddir"
+  # echo Using m2 at $M2_HOME
+fi
+
+# For Cygwin, ensure paths are in UNIX format before anything is touched
+if $cygwin ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --unix "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --unix "$CLASSPATH"`
+fi
+
+# For Mingw, ensure paths are in UNIX format before anything is touched
+if $mingw ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME="`(cd "$M2_HOME"; pwd)`"
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME="`(cd "$JAVA_HOME"; pwd)`"
+fi
+
+if [ -z "$JAVA_HOME" ]; then
+  javaExecutable="`which javac`"
+  if [ -n "$javaExecutable" ] && ! [ "`expr \"$javaExecutable\" : '\([^ ]*\)'`" = "no" ]; then
+    # readlink(1) is not available as standard on Solaris 10.
+    readLink=`which readlink`
+    if [ ! `expr "$readLink" : '\([^ ]*\)'` = "no" ]; then
+      if $darwin ; then
+        javaHome="`dirname \"$javaExecutable\"`"
+        javaExecutable="`cd \"$javaHome\" && pwd -P`/javac"
+      else
+        javaExecutable="`readlink -f \"$javaExecutable\"`"
+      fi
+      javaHome="`dirname \"$javaExecutable\"`"
+      javaHome=`expr "$javaHome" : '\(.*\)/bin'`
+      JAVA_HOME="$javaHome"
+      export JAVA_HOME
+    fi
+  fi
+fi
+
+if [ -z "$JAVACMD" ] ; then
+  if [ -n "$JAVA_HOME"  ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+      # IBM's JDK on AIX uses strange locations for the executables
+      JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+      JAVACMD="$JAVA_HOME/bin/java"
+    fi
+  else
+    JAVACMD="`\\unset -f command; \\command -v java`"
+  fi
+fi
+
+if [ ! -x "$JAVACMD" ] ; then
+  echo "Error: JAVA_HOME is not defined correctly." >&2
+  echo "  We cannot execute $JAVACMD" >&2
+  exit 1
+fi
+
+if [ -z "$JAVA_HOME" ] ; then
+  echo "Warning: JAVA_HOME environment variable is not set."
+fi
+
+CLASSWORLDS_LAUNCHER=org.codehaus.plexus.classworlds.launcher.Launcher
+
+# traverses directory structure from process work directory to filesystem root
+# first directory with .mvn subdirectory is considered project base directory
+find_maven_basedir() {
+
+  if [ -z "$1" ]
+  then
+    echo "Path not specified to find_maven_basedir"
+    return 1
+  fi
+
+  basedir="$1"
+  wdir="$1"
+  while [ "$wdir" != '/' ] ; do
+    if [ -d "$wdir"/.mvn ] ; then
+      basedir=$wdir
+      break
+    fi
+    # workaround for JBEAP-8937 (on Solaris 10/Sparc)
+    if [ -d "${wdir}" ]; then
+      wdir=`cd "$wdir/.."; pwd`
+    fi
+    # end of workaround
+  done
+  echo "${basedir}"
+}
+
+# concatenates all lines of a file
+concat_lines() {
+  if [ -f "$1" ]; then
+    echo "$(tr -s '\n' ' ' < "$1")"
+  fi
+}
+
+BASE_DIR=`find_maven_basedir "$(pwd)"`
+if [ -z "$BASE_DIR" ]; then
+  exit 1;
+fi
+
+##########################################################################################
+# Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+# This allows using the maven wrapper in projects that prohibit checking in binary data.
+##########################################################################################
+if [ -r "$BASE_DIR/.mvn/wrapper/maven-wrapper.jar" ]; then
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Found .mvn/wrapper/maven-wrapper.jar"
+    fi
+else
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Couldn't find .mvn/wrapper/maven-wrapper.jar, downloading it ..."
+    fi
+    if [ -n "$MVNW_REPOURL" ]; then
+      jarUrl="$MVNW_REPOURL/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar"
+    else
+      jarUrl="https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar"
+    fi
+    while IFS="=" read key value; do
+      case "$key" in (wrapperUrl) jarUrl="$value"; break ;;
+      esac
+    done < "$BASE_DIR/.mvn/wrapper/maven-wrapper.properties"
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Downloading from: $jarUrl"
+    fi
+    wrapperJarPath="$BASE_DIR/.mvn/wrapper/maven-wrapper.jar"
+    if $cygwin; then
+      wrapperJarPath=`cygpath --path --windows "$wrapperJarPath"`
+    fi
+
+    if command -v wget > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found wget ... using wget"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            wget "$jarUrl" -O "$wrapperJarPath" || rm -f "$wrapperJarPath"
+        else
+            wget --http-user=$MVNW_USERNAME --http-password=$MVNW_PASSWORD "$jarUrl" -O "$wrapperJarPath" || rm -f "$wrapperJarPath"
+        fi
+    elif command -v curl > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found curl ... using curl"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            curl -o "$wrapperJarPath" "$jarUrl" -f
+        else
+            curl --user $MVNW_USERNAME:$MVNW_PASSWORD -o "$wrapperJarPath" "$jarUrl" -f
+        fi
+
+    else
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Falling back to using Java to download"
+        fi
+        javaClass="$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.java"
+        # For Cygwin, switch paths to Windows format before running javac
+        if $cygwin; then
+          javaClass=`cygpath --path --windows "$javaClass"`
+        fi
+        if [ -e "$javaClass" ]; then
+            if [ ! -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Compiling MavenWrapperDownloader.java ..."
+                fi
+                # Compiling the Java class
+                ("$JAVA_HOME/bin/javac" "$javaClass")
+            fi
+            if [ -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                # Running the downloader
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Running MavenWrapperDownloader.java ..."
+                fi
+                ("$JAVA_HOME/bin/java" -cp .mvn/wrapper MavenWrapperDownloader "$MAVEN_PROJECTBASEDIR")
+            fi
+        fi
+    fi
+fi
+##########################################################################################
+# End of extension
+##########################################################################################
+
+export MAVEN_PROJECTBASEDIR=${MAVEN_BASEDIR:-"$BASE_DIR"}
+if [ "$MVNW_VERBOSE" = true ]; then
+  echo $MAVEN_PROJECTBASEDIR
+fi
+MAVEN_OPTS="$(concat_lines "$MAVEN_PROJECTBASEDIR/.mvn/jvm.config") $MAVEN_OPTS"
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --path --windows "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --path --windows "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --windows "$CLASSPATH"`
+  [ -n "$MAVEN_PROJECTBASEDIR" ] &&
+    MAVEN_PROJECTBASEDIR=`cygpath --path --windows "$MAVEN_PROJECTBASEDIR"`
+fi
+
+# Provide a "standardized" way to retrieve the CLI args that will
+# work with both Windows and non-Windows executions.
+MAVEN_CMD_LINE_ARGS="$MAVEN_CONFIG $@"
+export MAVEN_CMD_LINE_ARGS
+
+WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+exec "$JAVACMD" \
+  $MAVEN_OPTS \
+  $MAVEN_DEBUG_OPTS \
+  -classpath "$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.jar" \
+  "-Dmaven.home=${M2_HOME}" \
+  "-Dmaven.multiModuleProjectDirectory=${MAVEN_PROJECTBASEDIR}" \
+  ${WRAPPER_LAUNCHER} $MAVEN_CONFIG "$@"

spring-boot/spring-boot-null-safe-annotations/mvnw.cmd

@@ -0,0 +1,188 @@
+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements.  See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership.  The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License.  You may obtain a copy of the License at
+@REM
+@REM    https://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied.  See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Maven Start Up Batch script
+@REM
+@REM Required ENV vars:
+@REM JAVA_HOME - location of a JDK home dir
+@REM
+@REM Optional ENV vars
+@REM M2_HOME - location of maven2's installed home dir
+@REM MAVEN_BATCH_ECHO - set to 'on' to enable the echoing of the batch commands
+@REM MAVEN_BATCH_PAUSE - set to 'on' to wait for a keystroke before ending
+@REM MAVEN_OPTS - parameters passed to the Java VM when running Maven
+@REM     e.g. to debug Maven itself, use
+@REM set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+@REM MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+@REM ----------------------------------------------------------------------------
+
+@REM Begin all REM lines with '@' in case MAVEN_BATCH_ECHO is 'on'
+@echo off
+@REM set title of command window
+title %0
+@REM enable echoing by setting MAVEN_BATCH_ECHO to 'on'
+@if "%MAVEN_BATCH_ECHO%" == "on"  echo %MAVEN_BATCH_ECHO%
+
+@REM set %HOME% to equivalent of $HOME
+if "%HOME%" == "" (set "HOME=%HOMEDRIVE%%HOMEPATH%")
+
+@REM Execute a user defined script before this one
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPre
+@REM check for pre script, once with legacy .bat ending and once with .cmd ending
+if exist "%USERPROFILE%\mavenrc_pre.bat" call "%USERPROFILE%\mavenrc_pre.bat" %*
+if exist "%USERPROFILE%\mavenrc_pre.cmd" call "%USERPROFILE%\mavenrc_pre.cmd" %*
+:skipRcPre
+
+@setlocal
+
+set ERROR_CODE=0
+
+@REM To isolate internal variables from possible post scripts, we use another setlocal
+@setlocal
+
+@REM ==== START VALIDATION ====
+if not "%JAVA_HOME%" == "" goto OkJHome
+
+echo.
+echo Error: JAVA_HOME not found in your environment. >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+:OkJHome
+if exist "%JAVA_HOME%\bin\java.exe" goto init
+
+echo.
+echo Error: JAVA_HOME is set to an invalid directory. >&2
+echo JAVA_HOME = "%JAVA_HOME%" >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+@REM ==== END VALIDATION ====
+
+:init
+
+@REM Find the project base dir, i.e. the directory that contains the folder ".mvn".
+@REM Fallback to current working directory if not found.
+
+set MAVEN_PROJECTBASEDIR=%MAVEN_BASEDIR%
+IF NOT "%MAVEN_PROJECTBASEDIR%"=="" goto endDetectBaseDir
+
+set EXEC_DIR=%CD%
+set WDIR=%EXEC_DIR%
+:findBaseDir
+IF EXIST "%WDIR%"\.mvn goto baseDirFound
+cd ..
+IF "%WDIR%"=="%CD%" goto baseDirNotFound
+set WDIR=%CD%
+goto findBaseDir
+
+:baseDirFound
+set MAVEN_PROJECTBASEDIR=%WDIR%
+cd "%EXEC_DIR%"
+goto endDetectBaseDir
+
+:baseDirNotFound
+set MAVEN_PROJECTBASEDIR=%EXEC_DIR%
+cd "%EXEC_DIR%"
+
+:endDetectBaseDir
+
+IF NOT EXIST "%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config" goto endReadAdditionalConfig
+
+@setlocal EnableExtensions EnableDelayedExpansion
+for /F "usebackq delims=" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do set JVM_CONFIG_MAVEN_PROPS=!JVM_CONFIG_MAVEN_PROPS! %%a
+@endlocal & set JVM_CONFIG_MAVEN_PROPS=%JVM_CONFIG_MAVEN_PROPS%
+
+:endReadAdditionalConfig
+
+SET MAVEN_JAVA_EXE="%JAVA_HOME%\bin\java.exe"
+set WRAPPER_JAR="%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.jar"
+set WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+set DOWNLOAD_URL="https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar"
+
+FOR /F "usebackq tokens=1,2 delims==" %%A IN ("%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.properties") DO (
+    IF "%%A"=="wrapperUrl" SET DOWNLOAD_URL=%%B
+)
+
+@REM Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+@REM This allows using the maven wrapper in projects that prohibit checking in binary data.
+if exist %WRAPPER_JAR% (
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Found %WRAPPER_JAR%
+    )
+) else (
+    if not "%MVNW_REPOURL%" == "" (
+        SET DOWNLOAD_URL="%MVNW_REPOURL%/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar"
+    )
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Couldn't find %WRAPPER_JAR%, downloading it ...
+        echo Downloading from: %DOWNLOAD_URL%
+    )
+
+    powershell -Command "&{"^
+		"$webclient = new-object System.Net.WebClient;"^
+		"if (-not ([string]::IsNullOrEmpty('%MVNW_USERNAME%') -and [string]::IsNullOrEmpty('%MVNW_PASSWORD%'))) {"^
+		"$webclient.Credentials = new-object System.Net.NetworkCredential('%MVNW_USERNAME%', '%MVNW_PASSWORD%');"^
+		"}"^
+		"[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $webclient.DownloadFile('%DOWNLOAD_URL%', '%WRAPPER_JAR%')"^
+		"}"
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Finished downloading %WRAPPER_JAR%
+    )
+)
+@REM End of extension
+
+@REM Provide a "standardized" way to retrieve the CLI args that will
+@REM work with both Windows and non-Windows executions.
+set MAVEN_CMD_LINE_ARGS=%*
+
+%MAVEN_JAVA_EXE% ^
+  %JVM_CONFIG_MAVEN_PROPS% ^
+  %MAVEN_OPTS% ^
+  %MAVEN_DEBUG_OPTS% ^
+  -classpath %WRAPPER_JAR% ^
+  "-Dmaven.multiModuleProjectDirectory=%MAVEN_PROJECTBASEDIR%" ^
+  %WRAPPER_LAUNCHER% %MAVEN_CONFIG% %*
+if ERRORLEVEL 1 goto error
+goto end
+
+:error
+set ERROR_CODE=1
+
+:end
+@endlocal & set ERROR_CODE=%ERROR_CODE%
+
+if not "%MAVEN_SKIP_RC%"=="" goto skipRcPost
+@REM check for post script, once with legacy .bat ending and once with .cmd ending
+if exist "%USERPROFILE%\mavenrc_post.bat" call "%USERPROFILE%\mavenrc_post.bat"
+if exist "%USERPROFILE%\mavenrc_post.cmd" call "%USERPROFILE%\mavenrc_post.cmd"
+:skipRcPost
+
+@REM pause the script if MAVEN_BATCH_PAUSE is set to 'on'
+if "%MAVEN_BATCH_PAUSE%"=="on" pause
+
+if "%MAVEN_TERMINATE_CMD%"=="on" exit %ERROR_CODE%
+
+cmd /C exit /B %ERROR_CODE%

spring-boot/spring-boot-null-safe-annotations/pom.xml

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>2.6.2</version>
+		<relativePath /> <!-- lookup parent from repository -->
+	</parent>
+	<groupId>io.reflectoring</groupId>
+	<artifactId>spring-boot-null-safe-annotations</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<name>spring-boot-null-safe-annotations</name>
+	<description>Demo project for Spring Boot</description>
+	<properties>
+		<java.version>11</java.version>
+	</properties>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+			<plugin>
+				<groupId>com.github.spotbugs</groupId>
+				<artifactId>spotbugs-maven-plugin</artifactId>
+				<version>4.5.2.0</version>
+				<dependencies>
+					<!-- overwrite dependency on spotbugs if you want to specify the version of spotbugs -->
+					<dependency>
+						<groupId>com.github.spotbugs</groupId>
+						<artifactId>spotbugs</artifactId>
+						<version>4.5.3</version>
+					</dependency>
+				</dependencies>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

spring-boot/spring-boot-null-safe-annotations/src/main/java/io/reflectoring/nullsafety/Application.java

@@ -0,0 +1,13 @@
+package io.reflectoring.nullsafety;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+
+	public static void main(String[] args) {
+		SpringApplication.run(Application.class, args);
+	}
+
+}

spring-boot/spring-boot-null-safe-annotations/src/main/java/io/reflectoring/nullsafety/Employee.java

@@ -0,0 +1,47 @@
+package io.reflectoring.nullsafety;
+
+import java.time.LocalDate;
+
+import org.springframework.lang.NonNull;
+import org.springframework.lang.Nullable;
+
+class Employee {
+
+    @NonNull
+    String id;
+    String name;
+    LocalDate joiningDate;
+    @Nullable
+    String pastEmployment;
+
+    // constructor
+
+    public Employee(String id, String name, LocalDate joiningDate) {
+        this.id = id;
+        this.name = name;
+        this.joiningDate = joiningDate;
+    }
+
+    // standard getters-setters
+
+    String getId() {
+        return id;
+    }
+
+    String getName() {
+        return name;
+    }
+
+    LocalDate getJoiningDate() {
+        return joiningDate;
+    }
+
+    @Nullable
+    String getPastEmployment() {
+        return pastEmployment;
+    }
+
+    void setPastEmployment(@Nullable String pastEmployment) {
+        this.pastEmployment = pastEmployment;
+    }
+}

spring-boot/spring-boot-null-safe-annotations/src/main/java/io/reflectoring/nullsafety/package-info.java

@@ -0,0 +1,4 @@
+@NonNullApi
+package io.reflectoring.nullsafety;
+
+import org.springframework.lang.NonNullApi;

spring-boot/spring-boot-null-safe-annotations/src/main/resources/application.properties

@@ -0,0 +1 @@
+

spring-boot/spring-boot-null-safe-annotations/src/test/java/io/reflectoring/nullsafety/ApplicationTests.java

@@ -0,0 +1,13 @@
+package io.reflectoring.nullsafety;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class ApplicationTests {
+
+	@Test
+	void contextLoads() {
+	}
+
+}

spring-boot/spring-boot-null-safe-annotations/src/test/java/io/reflectoring/nullsafety/EmployeeTest.java

@@ -0,0 +1,25 @@
+package io.reflectoring.nullsafety;
+
+import static org.junit.jupiter.api.Assertions.assertAll;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import java.time.LocalDate;
+
+import org.junit.jupiter.api.Test;
+
+class EmployeeTest {
+
+    @Test
+    void employeeShouldHaveValidDetails() {
+        final Employee employee = new Employee("ID001", "Jane Dia", LocalDate.of(2019, 12, 31));
+        employee.setPastEmployment(null);
+        assertAll(() -> {
+            assertNotNull(employee.getId());
+            assertNotNull(employee.getName());
+            assertNotNull(employee.getJoiningDate());
+            assertNull(employee.getPastEmployment());
+        });
+    }
+
+}

spring-boot/thymeleaf-vue/client/package-lock.json

@@ -15383,9 +15383,9 @@
       "dev": true
     },
     "shelljs": {
-      "version": "0.8.4",
-      "resolved": "https://registry.npmjs.org/shelljs/-/shelljs-0.8.4.tgz",
-      "integrity": "sha512-7gk3UZ9kOfPLIAbslLzyWeGiEqx9e3rxwZM0KE6EL8GlGwjym9Mrlx5/p33bWTu9YG6vcS4MBxYZDHYr5lr8BQ==",
+      "version": "0.8.5",
+      "resolved": "https://registry.npmjs.org/shelljs/-/shelljs-0.8.5.tgz",
+      "integrity": "sha512-TiwcRcrkhHvbrZbnRcFYMLl30Dfov3HKqzp5tO5b4pt6G/SezKcYhmDg15zXVBswHmctSAQKznqNW2LO5tTDow==",
       "dev": true,
       "requires": {
         "glob": "^7.0.0",

spring-cloud/tracing/README.md

@@ -6,4 +6,7 @@
 
 The above HTTP call goes to the `api-service`, which will call the `customer-service` for additional information. This will create a trace across both services, as should be evident in the logs with the same trace id.
 
-The `docker-compose` command also starts up an OpenTelemetry Collector, to which the Spring Boot apps send their traces. The OpenTelemetry Collector, in turn, sends the traces to Logz.io.
+The `docker-compose` command also starts up an OpenTelemetry Collector, to which the Spring Boot apps send their traces. The OpenTelemetry Collector, in turn, sends the traces to Logz.io.
+
+## Companion Article
+[Tracing with Spring Boot, OpenTelemetry, and Jaeger](https://reflectoring.io/spring-boot-tracing)