diff --git a/core-java-modules/core-java-string-algorithms-3/pom.xml b/core-java-modules/core-java-string-algorithms-3/pom.xml
index 6700e9ba95..180d75cc61 100644
--- a/core-java-modules/core-java-string-algorithms-3/pom.xml
+++ b/core-java-modules/core-java-string-algorithms-3/pom.xml
@@ -24,6 +24,11 @@
             <artifactId>commons-validator</artifactId>
             <version>${validator.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -49,8 +54,8 @@
     </build>
 
     <properties>
-        <guava.version>28.1-jre</guava.version>
+        <guava.version>31.0.1-jre</guava.version>
         <validator.version>1.7</validator.version>
     </properties>
 
-</project>
\ No newline at end of file
+</project>
diff --git a/core-java-modules/core-java-string-algorithms-2/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercase.java b/core-java-modules/core-java-string-algorithms-3/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercase.java
similarity index 100%
rename from core-java-modules/core-java-string-algorithms-2/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercase.java
rename to core-java-modules/core-java-string-algorithms-3/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercase.java
index 0d9d3b6431..f9edd005dc 100644
--- a/core-java-modules/core-java-string-algorithms-2/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercase.java
+++ b/core-java-modules/core-java-string-algorithms-3/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercase.java
@@ -1,9 +1,9 @@
 package com.baeldung.isuppercase;
 
-import com.google.common.base.Ascii;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.TestInstance;
+import com.google.common.base.Ascii;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.matchesPattern;
diff --git a/spring-boot-modules/spring-boot-swagger/src/main/java/com/baeldung/swagger2pdf/controller/UserController.java b/spring-boot-modules/spring-boot-swagger/src/main/java/com/baeldung/swagger2pdf/controller/UserController.java
deleted file mode 100644
index 380bac6f8c..0000000000
--- a/spring-boot-modules/spring-boot-swagger/src/main/java/com/baeldung/swagger2pdf/controller/UserController.java
+++ /dev/null
@@ -1,63 +0,0 @@
-package com.baeldung.swagger2pdf.controller;
-
-import com.baeldung.swagger2pdf.objects.User;
-import io.swagger.annotations.Api;
-import io.swagger.annotations.ApiOperation;
-import lombok.NonNull;
-import org.springframework.http.HttpStatus;
-import org.springframework.http.MediaType;
-import org.springframework.stereotype.Controller;
-import org.springframework.web.bind.annotation.*;
-
-import java.util.ArrayList;
-import java.util.List;
-
-@Controller
-@Api(value = "/api", description = "A controller for user management")
-@RequestMapping("/user")
-@ResponseStatus(HttpStatus.OK)
-public class UserController {
-
-    static List<User> users;
-
-    static {
-        users = new ArrayList<>();
-        users.add(new User("Mark", "Thompson", 23));
-        users.add(new User("Kate", "Jordan", 22));
-    }
-
-    @ApiOperation(value = "Retrieves all the users")
-    @RequestMapping(value = "/users",
-            method = RequestMethod.GET,
-            produces = MediaType.APPLICATION_JSON_VALUE)
-    public List<User> getUsers() {
-        return users;
-    }
-
-    @ApiOperation(value = "Retrieves a user based on first name")
-    @RequestMapping(value = "/user",
-            method = RequestMethod.GET,
-            produces = MediaType.APPLICATION_JSON_VALUE)
-    public User getUser(@NonNull @RequestParam String firstName) {
-
-        if (firstName.isEmpty()) {
-            return null;
-        }
-
-        return users.stream()
-                .filter(user -> user.getFirstName().equals(firstName))
-                .findAny()
-                .orElse(null);
-
-    }
-
-    @ApiOperation(value = "Adds a user.")
-    @RequestMapping(value = "/user",
-            method = RequestMethod.POST,
-            produces = MediaType.APPLICATION_JSON_VALUE)
-    public List<User> addUser(@NonNull @RequestBody User user) {
-        users.add(user);
-        return users;
-    }
-}
-
diff --git a/spring-boot-modules/spring-boot-swagger/src/main/java/com/baeldung/swagger2pdf/objects/User.java b/spring-boot-modules/spring-boot-swagger/src/main/java/com/baeldung/swagger2pdf/objects/User.java
deleted file mode 100644
index 8c59cb246a..0000000000
--- a/spring-boot-modules/spring-boot-swagger/src/main/java/com/baeldung/swagger2pdf/objects/User.java
+++ /dev/null
@@ -1,12 +0,0 @@
-package com.baeldung.swagger2pdf.objects;
-
-import lombok.AllArgsConstructor;
-import lombok.Data;
-
-@Data
-@AllArgsConstructor
-public class User {
-    private String firstName;
-    private String lastName;
-    private int age;
-}