Grouping by collector java (#10986)

* Initial Commit - Ports and Adapters

* Restructured code to implement input and outbou ports and adapters

* Added tests for groupingBy Collector

* Revert "Initial Commit - Ports and Adapters"

This reverts commit 55152dea

* Added tests for groupingBy Collector

* reverting

* corrected typo

* used BDD naming strategy for tests

* Added a test for groupingByConcurrent

* added new module and package

* added core-java-streams-4 module in main pom.xml

* updated pom.xml and changed artifactId

core-java-modules/core-java-streams-4/.gitignore

@@ -0,0 +1,26 @@
+*.class
+
+0.*
+
+#folders#
+/target
+/neoDb*
+/data
+/src/main/webapp/WEB-INF/classes
+*/META-INF/*
+.resourceCache
+
+# Packaged files #
+*.jar
+*.war
+*.ear
+
+# Files generated by integration tests
+*.txt
+backup-pom.xml
+/bin/
+/temp
+
+#IntelliJ specific
+.idea/
+*.iml