Merge branch 'eugenp:master' into master

.gitignore

@@ -89,5 +89,14 @@ testing-modules/report-*.json
 
 libraries-2/*.db
 
+apache-spark/data/output
+logs/
+libraries-data-io/*.docx
+persistence-modules/spring-hibernate-5/com.*
+spring-boot-modules/spring-boot-react/frontend/build
+spring-boot-modules/spring-boot-react/frontend/node
+spring-boot-modules/spring-boot-react/frontend/yarn.lock
+spring-boot-modules/spring-boot-properties-3/*.log
+
 # SDKMan
-.sdkmanrc
+.sdkmanrc

akka-http/pom.xml

@@ -1,8 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xmlns="http://maven.apache.org/POM/4.0.0"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
     <modelVersion>4.0.0</modelVersion>
     <artifactId>akka-http</artifactId>
     <name>akka-http</name>

akka-streams/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>

algorithms-genetic/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -44,18 +43,6 @@
         </dependency>
     </dependencies>
 
-    <build>
-        <pluginManagement>
-            <plugins>
-                <plugin>
-                    <groupId>org.codehaus.mojo</groupId>
-                    <artifactId>exec-maven-plugin</artifactId>
-                    <version>${exec-maven-plugin.version}</version>
-                </plugin>
-            </plugins>
-        </pluginManagement>
-    </build>
-
     <properties>
         <commons-math3.version>3.6.1</commons-math3.version>
         <io.jenetics.version>3.7.0</io.jenetics.version>
@@ -63,4 +50,4 @@
         <commons-codec.version>1.11</commons-codec.version>
     </properties>
 
-</project>
+</project>

algorithms-miscellaneous-1/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -49,18 +48,6 @@
         </dependency>
     </dependencies>
 
-    <build>
-        <pluginManagement>
-            <plugins>
-                <plugin>
-                    <groupId>org.codehaus.mojo</groupId>
-                    <artifactId>exec-maven-plugin</artifactId>
-                    <version>${exec-maven-plugin.version}</version>
-                </plugin>
-            </plugins>
-        </pluginManagement>
-    </build>
-
     <reporting>
         <plugins>
             <plugin>

algorithms-miscellaneous-2/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -54,18 +53,6 @@
         </dependency>
     </dependencies>
 
-    <build>
-        <pluginManagement>
-            <plugins>
-                <plugin>
-                    <groupId>org.codehaus.mojo</groupId>
-                    <artifactId>exec-maven-plugin</artifactId>
-                    <version>${exec-maven-plugin.version}</version>
-                </plugin>
-            </plugins>
-        </pluginManagement>
-    </build>
-
     <reporting>
         <plugins>
             <plugin>

algorithms-miscellaneous-2/src/test/java/com/baeldung/algorithms/astar/RouteFinder.java

@@ -8,6 +8,9 @@ import java.util.PriorityQueue;
 import java.util.Queue;
 import java.util.stream.Collectors;
 
+import lombok.extern.slf4j.Slf4j;
+
+@Slf4j
 public class RouteFinder<T extends GraphNode> {
     private final Graph<T> graph;
     private final Scorer<T> nextNodeScorer;
@@ -28,11 +31,11 @@ public class RouteFinder<T extends GraphNode> {
         openSet.add(start);
 
         while (!openSet.isEmpty()) {
-            System.out.println("Open Set contains: " + openSet.stream().map(RouteNode::getCurrent).collect(Collectors.toSet()));
+            log.debug("Open Set contains: " + openSet.stream().map(RouteNode::getCurrent).collect(Collectors.toSet()));
             RouteNode<T> next = openSet.poll();
-            System.out.println("Looking at node: " + next);
+            log.debug("Looking at node: " + next);
             if (next.getCurrent().equals(to)) {
-                System.out.println("Found our destination!");
+                log.debug("Found our destination!");
 
                 List<T> route = new ArrayList<>();
                 RouteNode<T> current = next;
@@ -41,7 +44,7 @@ public class RouteFinder<T extends GraphNode> {
                     current = allNodes.get(current.getPrevious());
                 } while (current != null);
 
-                System.out.println("Route: " + route);
+                log.debug("Route: " + route);
                 return route;
             }
 
@@ -55,7 +58,7 @@ public class RouteFinder<T extends GraphNode> {
                     nextNode.setRouteScore(newScore);
                     nextNode.setEstimatedScore(newScore + targetScorer.computeCost(connection, to));
                     openSet.add(nextNode);
-                    System.out.println("Found a better route to node: " + nextNode);
+                    log.debug("Found a better route to node: " + nextNode);
                 }
             });
         }

algorithms-miscellaneous-2/src/test/java/com/baeldung/algorithms/astar/underground/RouteFinderIntegrationTest.java

@@ -1,5 +1,7 @@
 package com.baeldung.algorithms.astar.underground;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -10,9 +12,13 @@ import java.util.stream.Stream;
 
 import com.baeldung.algorithms.astar.Graph;
 import com.baeldung.algorithms.astar.RouteFinder;
+
+import lombok.extern.slf4j.Slf4j;
+
 import org.junit.Before;
 import org.junit.Test;
 
+@Slf4j
 public class RouteFinderIntegrationTest {
 
     private Graph<Station> underground;
@@ -637,7 +643,8 @@ public class RouteFinderIntegrationTest {
     @Test
     public void findRoute() {
         List<Station> route = routeFinder.findRoute(underground.getNode("74"), underground.getNode("7"));
+        assertThat(route).size().isPositive();
 
-        System.out.println(route.stream().map(Station::getName).collect(Collectors.toList()));
+        route.stream().map(Station::getName).collect(Collectors.toList()).forEach(station -> log.debug(station));
     }
 }

algorithms-miscellaneous-3/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -21,19 +20,16 @@
             <version>${org.assertj.core.version}</version>
             <scope>test</scope>
         </dependency>
-
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-collections4</artifactId>
             <version>${commons-collections4.version}</version>
         </dependency>
-
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
             <version>${guava.version}</version>
         </dependency>
-
         <dependency>
             <groupId>com.squareup.retrofit2</groupId>
             <artifactId>retrofit</artifactId>
@@ -44,13 +40,11 @@
             <artifactId>converter-jackson</artifactId>
             <version>${retrofit.version}</version>
         </dependency>
-
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-lang3</artifactId>
             <version>${commons.lang3.version}</version>
         </dependency>
-
         <dependency>
             <groupId>pl.pragmatists</groupId>
             <artifactId>JUnitParams</artifactId>
@@ -74,18 +68,6 @@
         </dependency>
     </dependencies>
 
-    <build>
-        <pluginManagement>
-            <plugins>
-                <plugin>
-                    <groupId>org.codehaus.mojo</groupId>
-                    <artifactId>exec-maven-plugin</artifactId>
-                    <version>${exec-maven-plugin.version}</version>
-                </plugin>
-            </plugins>
-        </pluginManagement>
-    </build>
-
     <properties>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
         <commons-collections4.version>4.3</commons-collections4.version>

algorithms-miscellaneous-4/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -34,18 +33,6 @@
         </dependency>
     </dependencies>
 
-    <build>
-        <pluginManagement>
-            <plugins>
-                <plugin>
-                    <groupId>org.codehaus.mojo</groupId>
-                    <artifactId>exec-maven-plugin</artifactId>
-                    <version>${exec-maven-plugin.version}</version>
-                </plugin>
-            </plugins>
-        </pluginManagement>
-    </build>
-
     <properties>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
         <guava.version>27.0.1-jre</guava.version>

algorithms-miscellaneous-5/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -38,9 +37,8 @@
         <dependency>
             <groupId>org.junit.platform</groupId>
             <artifactId>junit-platform-commons</artifactId>
-            <version>${junit.platform.version}</version>
+            <version>${junit-platform.version}</version>
         </dependency>
-
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
@@ -49,25 +47,12 @@
         </dependency>
     </dependencies>
 
-    <build>
-        <pluginManagement>
-            <plugins>
-                <plugin>
-                    <groupId>org.codehaus.mojo</groupId>
-                    <artifactId>exec-maven-plugin</artifactId>
-                    <version>${exec-maven-plugin.version}</version>
-                </plugin>
-            </plugins>
-        </pluginManagement>
-    </build>
-
     <properties>
         <tradukisto.version>1.0.1</tradukisto.version>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
         <commons-codec.version>1.11</commons-codec.version>
         <commons-math3.version>3.6.1</commons-math3.version>
         <guava.version>28.1-jre</guava.version>
-        <junit.platform.version>1.6.0</junit.platform.version>
     </properties>
 
 </project>

algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/prim/PrimUnitTest.java

@@ -1,10 +1,10 @@
 package com.baeldung.algorithms.prim;
 
+import org.junit.Test;
+
 import java.util.ArrayList;
 import java.util.List;
 
-import org.junit.Test;
-
 public class PrimUnitTest {
 
     @Test

algorithms-miscellaneous-6/pom.xml

@@ -1,6 +1,7 @@
 <?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"
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <artifactId>algorithms-miscellaneous-6</artifactId>
     <version>0.0.1-SNAPSHOT</version>
@@ -11,9 +12,9 @@
         <artifactId>parent-modules</artifactId>
         <version>1.0.0-SNAPSHOT</version>
     </parent>
-    
+
     <dependencies>
-    <dependency>
+        <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
             <version>${guava.version}</version>
@@ -21,7 +22,7 @@
         <dependency>
             <groupId>org.junit.platform</groupId>
             <artifactId>junit-platform-commons</artifactId>
-            <version>${junit.platform.version}</version>
+            <version>${junit-platform.version}</version>
         </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
@@ -41,12 +42,11 @@
             <version>${commons-math3.version}</version>
         </dependency>
     </dependencies>
-    
+
     <properties>
         <guava.version>28.1-jre</guava.version>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
-        <junit.platform.version>1.6.0</junit.platform.version>
         <commons-math3.version>3.6.1</commons-math3.version>
     </properties>
 
-</project>
+</project>

algorithms-searching/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>

algorithms-searching/src/main/java/com/baeldung/algorithms/binarysearch/BinarySearch.java

@@ -12,7 +12,7 @@ public class BinarySearch {
 
         while (low <= high) {
 
-            int mid = (low + high) / 2;
+            int mid = low + ((high - low) / 2);
 
             if (sortedArray[mid] < key) {
                 low = mid + 1;
@@ -28,7 +28,7 @@ public class BinarySearch {
 
     public int runBinarySearchRecursively(int[] sortedArray, int key, int low, int high) {
 
-        int middle = (low + high) / 2;
+        int middle = low + ((high - low) / 2);
         if (high < low) {
             return -1;
         }

algorithms-searching/src/main/java/com/baeldung/algorithms/dfs/Graph.java

@@ -29,11 +29,13 @@ public class Graph {
         stack.push(start);
         while (!stack.isEmpty()) {
             int current = stack.pop();
-            isVisited[current] = true;
+            if(!isVisited[current]){
-            visit(current);
+                isVisited[current] = true;
-            for (int dest : adjVertices.get(current)) {
+                visit(current);
-                if (!isVisited[dest])
+                for (int dest : adjVertices.get(current)) {
-                    stack.push(dest);
+                    if (!isVisited[dest])
+                        stack.push(dest);
+                }
             }
         }
     }

algorithms-searching/src/main/java/com/baeldung/algorithms/suffixtree/SuffixTree.java

@@ -8,7 +8,9 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 public class SuffixTree {
+
     private static final Logger LOGGER = LoggerFactory.getLogger(SuffixTree.class);
+
     private static final String WORD_TERMINATION = "$";
     private static final int POSITION_UNDEFINED = -1;
     private Node root;
@@ -23,7 +25,7 @@ public class SuffixTree {
     }
 
     public List<String> searchText(String pattern) {
-        LOGGER.info("Searching for pattern \"{}\"", pattern);
+        LOGGER.debug("Searching for pattern \"{}\"", pattern);
         List<String> result = new ArrayList<>();
         List<Node> nodes = getAllNodesInTraversePath(pattern, root, false);
 
@@ -41,11 +43,11 @@ public class SuffixTree {
     }
 
     private void addSuffix(String suffix, int position) {
-        LOGGER.info(">>>>>>>>>>>> Adding new suffix {}", suffix);
+        LOGGER.debug(">>>>>>>>>>>> Adding new suffix {}", suffix);
         List<Node> nodes = getAllNodesInTraversePath(suffix, root, true);
         if (nodes.size() == 0) {
             addChildNode(root, suffix, position);
-            LOGGER.info("{}", printTree());
+            LOGGER.debug("{}", printTree());
         } else {
             Node lastNode = nodes.remove(nodes.size() - 1);
             String newText = suffix;
@@ -58,7 +60,7 @@ public class SuffixTree {
                 newText = newText.substring(existingSuffixUptoLastNode.length());
             }
             extendNode(lastNode, newText, position);
-            LOGGER.info("{}", printTree());
+            LOGGER.debug("{}", printTree());
         }
     }
 

algorithms-searching/src/test/java/com/baeldung/algorithms/dfs/GraphUnitTest.java

@@ -2,7 +2,6 @@ package com.baeldung.algorithms.dfs;
 
 import java.util.List;
 
-import com.baeldung.algorithms.dfs.Graph;
 import org.junit.Test;
 
 public class GraphUnitTest {

algorithms-searching/src/test/java/com/baeldung/algorithms/quadtree/QuadTreeSearchUnitTest.java

@@ -10,7 +10,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 public class QuadTreeSearchUnitTest {
-    
+
     private static final Logger LOGGER = LoggerFactory.getLogger(QuadTreeSearchUnitTest.class);
 
     private static QuadTree quadTree;
@@ -20,41 +20,41 @@ public class QuadTreeSearchUnitTest {
         Region area = new Region(0, 0, 400, 400);
         quadTree = new QuadTree(area);
 
-        float[][] points = new float[][] { { 21, 25 }, { 55, 53 }, { 70, 318 }, { 98, 302 }, 
+        float[][] points = new float[][] { { 21, 25 }, { 55, 53 }, { 70, 318 }, { 98, 302 },
             { 49, 229 }, { 135, 229 }, { 224, 292 }, { 206, 321 }, { 197, 258 }, { 245, 238 } };
 
         for (int i = 0; i < points.length; i++) {
             Point point = new Point(points[i][0], points[i][1]);
             quadTree.addPoint(point);
         }
-        LOGGER.info("\n" + quadTree.printTree(""));
+        LOGGER.debug("\n" + quadTree.printTree(""));
-        LOGGER.info("==============================================");
+        LOGGER.debug("==============================================");
     }
 
     @Test
     public void givenQuadTree_whenSearchingForRange_thenReturn1MatchingItem() {
         Region searchArea = new Region(200, 200, 250, 250);
         List<Point> result = quadTree.search(searchArea, null, "");
-        LOGGER.info(result.toString());
+        LOGGER.debug(result.toString());
-        LOGGER.info(quadTree.printSearchTraversePath());
+        LOGGER.debug(quadTree.printSearchTraversePath());
-       
+
         Assert.assertEquals(1, result.size());
-        Assert.assertArrayEquals(new float[] { 245, 238 }, 
+        Assert.assertArrayEquals(new float[] { 245, 238 },
             new float[]{result.get(0).getX(), result.get(0).getY() }, 0);
     }
-    
+
     @Test
     public void givenQuadTree_whenSearchingForRange_thenReturn2MatchingItems() {
         Region searchArea = new Region(0, 0, 100, 100);
         List<Point> result = quadTree.search(searchArea, null, "");
-        LOGGER.info(result.toString());
+        LOGGER.debug(result.toString());
-        LOGGER.info(quadTree.printSearchTraversePath());
+        LOGGER.debug(quadTree.printSearchTraversePath());
-        
+
         Assert.assertEquals(2, result.size());
-        Assert.assertArrayEquals(new float[] { 21, 25 }, 
+        Assert.assertArrayEquals(new float[] { 21, 25 },
             new float[]{result.get(0).getX(), result.get(0).getY() }, 0);
-        Assert.assertArrayEquals(new float[] { 55, 53 }, 
+        Assert.assertArrayEquals(new float[] { 55, 53 },
             new float[]{result.get(1).getX(), result.get(1).getY() }, 0);
-        
+
     }
 }

algorithms-sorting-2/pom.xml

@@ -1,5 +1,4 @@
-<project
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="http://maven.apache.org/POM/4.0.0"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -33,7 +32,7 @@
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-api</artifactId>
-            <version>${junit-jupiter-api.version}</version>
+            <version>${junit-jupiter.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
@@ -44,23 +43,10 @@
         </dependency>
     </dependencies>
 
-    <build>
-        <pluginManagement>
-            <plugins>
-                <plugin>
-                    <groupId>org.codehaus.mojo</groupId>
-                    <artifactId>exec-maven-plugin</artifactId>
-                    <version>${exec-maven-plugin.version}</version>
-                </plugin>
-            </plugins>
-        </pluginManagement>
-    </build>
-
     <properties>
         <commons-math3.version>3.6.1</commons-math3.version>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
         <commons-codec.version>1.11</commons-codec.version>
-        <junit-jupiter-api.version>5.3.1</junit-jupiter-api.version>
     </properties>
 
 </project>

algorithms-sorting/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -34,7 +33,7 @@
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-api</artifactId>
-            <version>${junit-jupiter-api.version}</version>
+            <version>${junit-jupiter.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
@@ -45,23 +44,10 @@
         </dependency>
     </dependencies>
 
-    <build>
-        <pluginManagement>
-            <plugins>
-                <plugin>
-                    <groupId>org.codehaus.mojo</groupId>
-                    <artifactId>exec-maven-plugin</artifactId>
-                    <version>${exec-maven-plugin.version}</version>
-                </plugin>
-            </plugins>
-        </pluginManagement>
-    </build>
-
     <properties>
         <commons-math3.version>3.6.1</commons-math3.version>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
         <commons-codec.version>1.11</commons-codec.version>
-        <junit-jupiter-api.version>5.3.1</junit-jupiter-api.version>
     </properties>
 
 </project>

animal-sniffer-mvn-plugin/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>

annotations/annotation-processing/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="http://maven.apache.org/POM/4.0.0"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -11,7 +10,6 @@
         <groupId>com.baeldung</groupId>
         <version>1.0.0-SNAPSHOT</version>
         <artifactId>annotations</artifactId>
-        <relativePath>../</relativePath>
     </parent>
 
     <dependencies>

annotations/annotation-user/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -11,7 +10,6 @@
         <groupId>com.baeldung</groupId>
         <artifactId>annotations</artifactId>
         <version>1.0.0-SNAPSHOT</version>
-        <relativePath>../</relativePath>
     </parent>
 
     <dependencies>

annotations/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>

antlr/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>

apache-cxf/cxf-aegis/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -21,4 +20,4 @@
         </dependency>
     </dependencies>
 
-</project>
+</project>

apache-cxf/cxf-introduction/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -38,4 +37,4 @@
         </plugins>
     </build>
 
-</project>
+</project>

apache-cxf/cxf-jaxrs-implementation/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -53,4 +52,4 @@
         <httpclient.version>4.5.2</httpclient.version>
     </properties>
 
-</project>
+</project>

apache-cxf/cxf-spring/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -108,4 +107,4 @@
         <cargo-maven2-plugin.version>1.6.1</cargo-maven2-plugin.version>
     </properties>
 
-</project>
+</project>

apache-cxf/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -30,7 +29,6 @@
                 <plugin>
                     <groupId>org.codehaus.mojo</groupId>
                     <artifactId>exec-maven-plugin</artifactId>
-                    <version>${exec-maven-plugin.version}</version>
                 </plugin>
             </plugins>
         </pluginManagement>
@@ -40,4 +38,4 @@
         <cxf.version>3.1.8</cxf.version>
     </properties>
 
-</project>
+</project>

apache-cxf/sse-jaxrs/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -19,4 +18,4 @@
         <module>sse-jaxrs-client</module>
     </modules>
 
-</project>
+</project>

apache-cxf/sse-jaxrs/sse-jaxrs-client/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -59,4 +58,4 @@
         <cxf-version>3.2.0</cxf-version>
     </properties>
 
-</project>
+</project>

apache-cxf/sse-jaxrs/sse-jaxrs-server/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -15,7 +14,6 @@
     </parent>
 
     <dependencies>
-
         <dependency>
             <groupId>javax.ws.rs</groupId>
             <artifactId>javax.ws.rs-api</artifactId>
@@ -34,7 +32,6 @@
             <version>${bind-api.version}</version>
             <scope>provided</scope>
         </dependency>
-
     </dependencies>
 
     <build>
@@ -86,4 +83,4 @@
         <bind-api.version>1.0</bind-api.version>
     </properties>
 
-</project>
+</project>

apache-kafka/README.md

@@ -0,0 +1,19 @@
+## Apache Kafka
+
+This module contains articles about Apache Kafka.
+
+### Relevant articles
+- [Kafka Streams vs. Kafka Consumer](https://www.baeldung.com/java-kafka-streams-vs-kafka-consumer)
+- [Kafka Topic Creation Using Java](https://www.baeldung.com/kafka-topic-creation)
+- [Using Kafka MockConsumer](https://www.baeldung.com/kafka-mockconsumer)
+- [Using Kafka MockProducer](https://www.baeldung.com/kafka-mockproducer)
+- [Introduction to KafkaStreams in Java](https://www.baeldung.com/java-kafka-streams)
+- [Introduction to Kafka Connectors](https://www.baeldung.com/kafka-connectors-guide)
+- [Kafka Connect Example with MQTT and MongoDB](https://www.baeldung.com/kafka-connect-mqtt-mongodb)
+- [Building a Data Pipeline with Flink and Kafka](https://www.baeldung.com/kafka-flink-data-pipeline)
+- [Exactly Once Processing in Kafka with Java](https://www.baeldung.com/kafka-exactly-once)
+- [Custom Serializers in Apache Kafka](https://www.baeldung.com/kafka-custom-serializer)
+
+
+##### Building the project
+You can build the project from the command line using: *mvn clean install*, or in an IDE.

apache-kafka/log4j.properties

@@ -0,0 +1 @@
+log4j.rootLogger=INFO, stdout

apache-kafka/pom.xml

@@ -0,0 +1,187 @@
+<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>apache-kafka</artifactId>
+    <name>apache-kafka</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.kafka</groupId>
+            <artifactId>kafka-clients</artifactId>
+            <version>${kafka.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.kafka</groupId>
+            <artifactId>kafka-streams</artifactId>
+            <version>${kafka.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-log4j12</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.flink</groupId>
+            <artifactId>flink-connector-kafka-0.11_2.11</artifactId>
+            <version>${flink.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.flink</groupId>
+            <artifactId>flink-streaming-java_2.11</artifactId>
+            <version>${flink.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.flink</groupId>
+            <artifactId>flink-core</artifactId>
+            <version>${flink.version}</version>
+            <exclusions>
+                <exclusion>
+                    <artifactId>commons-logging</artifactId>
+                    <groupId>commons-logging</groupId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.flink</groupId>
+            <artifactId>flink-java</artifactId>
+            <version>${flink.version}</version>
+            <exclusions>
+                <exclusion>
+                    <artifactId>commons-logging</artifactId>
+                    <groupId>commons-logging</groupId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.flink</groupId>
+            <artifactId>flink-test-utils_2.11</artifactId>
+            <version>${flink.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.awaitility</groupId>
+            <artifactId>awaitility</artifactId>
+            <version>${awaitility.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.awaitility</groupId>
+            <artifactId>awaitility-proxy</artifactId>
+            <version>${awaitility.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.datatype</groupId>
+            <artifactId>jackson-datatype-jsr310</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>kafka</artifactId>
+            <version>${testcontainers-kafka.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${testcontainers-jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-core_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-sql_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-graphx_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-streaming_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-mllib_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-streaming-kafka-0-10_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.datastax.spark</groupId>
+            <artifactId>spark-cassandra-connector_2.11</artifactId>
+            <version>${com.datastax.spark.spark-cassandra-connector.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.datastax.spark</groupId>
+            <artifactId>spark-cassandra-connector-java_2.11</artifactId>
+            <version>${com.datastax.spark.spark-cassandra-connector-java.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <assertj.version>3.6.2</assertj.version>
+        <kafka.version>2.8.0</kafka.version>
+        <testcontainers-kafka.version>1.15.3</testcontainers-kafka.version>
+        <testcontainers-jupiter.version>1.15.3</testcontainers-jupiter.version>
+        <flink.version>1.5.0</flink.version>
+        <awaitility.version>3.0.0</awaitility.version>
+        <guava.version>29.0-jre</guava.version>
+        <org.apache.spark.spark-core.version>2.4.8</org.apache.spark.spark-core.version>
+        <graphframes.version>0.8.1-spark3.0-s_2.12</graphframes.version>
+        <com.datastax.spark.spark-cassandra-connector.version>2.5.2</com.datastax.spark.spark-cassandra-connector.version>
+        <com.datastax.spark.spark-cassandra-connector-java.version>1.6.0-M1</com.datastax.spark.spark-cassandra-connector-java.version>
+        <lombok.version>1.18.20</lombok.version>
+    </properties>
+
+</project>

apache-kafka/src/main/java/com/baeldung/flink/FlinkDataPipeline.java

@@ -0,0 +1,70 @@
+package com.baeldung.flink;
+
+import com.baeldung.flink.model.Backup;
+import com.baeldung.flink.model.InputMessage;
+import com.baeldung.flink.operator.BackupAggregator;
+import com.baeldung.flink.operator.InputMessageTimestampAssigner;
+import com.baeldung.flink.operator.WordsCapitalizer;
+import org.apache.flink.streaming.api.TimeCharacteristic;
+import org.apache.flink.streaming.api.datastream.DataStream;
+import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
+import org.apache.flink.streaming.api.windowing.time.Time;
+import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer011;
+import org.apache.flink.streaming.connectors.kafka.FlinkKafkaProducer011;
+
+import static com.baeldung.flink.connector.Consumers.*;
+import static com.baeldung.flink.connector.Producers.*;
+
+public class FlinkDataPipeline {
+
+    public static void capitalize() throws Exception {
+        String inputTopic = "flink_input";
+        String outputTopic = "flink_output";
+        String consumerGroup = "baeldung";
+        String address = "localhost:9092";
+
+        StreamExecutionEnvironment environment = StreamExecutionEnvironment.getExecutionEnvironment();
+
+        FlinkKafkaConsumer011<String> flinkKafkaConsumer = createStringConsumerForTopic(inputTopic, address, consumerGroup);
+        flinkKafkaConsumer.setStartFromEarliest();
+
+        DataStream<String> stringInputStream = environment.addSource(flinkKafkaConsumer);
+
+        FlinkKafkaProducer011<String> flinkKafkaProducer = createStringProducer(outputTopic, address);
+
+        stringInputStream.map(new WordsCapitalizer())
+            .addSink(flinkKafkaProducer);
+
+        environment.execute();
+    }
+
+    public static void createBackup() throws Exception {
+        String inputTopic = "flink_input";
+        String outputTopic = "flink_output";
+        String consumerGroup = "baeldung";
+        String kafkaAddress = "localhost:9092";
+
+        StreamExecutionEnvironment environment = StreamExecutionEnvironment.getExecutionEnvironment();
+
+        environment.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);
+
+        FlinkKafkaConsumer011<InputMessage> flinkKafkaConsumer = createInputMessageConsumer(inputTopic, kafkaAddress, consumerGroup);
+        flinkKafkaConsumer.setStartFromEarliest();
+
+        flinkKafkaConsumer.assignTimestampsAndWatermarks(new InputMessageTimestampAssigner());
+        FlinkKafkaProducer011<Backup> flinkKafkaProducer = createBackupProducer(outputTopic, kafkaAddress);
+
+        DataStream<InputMessage> inputMessagesStream = environment.addSource(flinkKafkaConsumer);
+
+        inputMessagesStream.timeWindowAll(Time.hours(24))
+            .aggregate(new BackupAggregator())
+            .addSink(flinkKafkaProducer);
+
+        environment.execute();
+    }
+
+    public static void main(String[] args) throws Exception {
+        createBackup();
+    }
+
+}

apache-kafka/src/main/java/com/baeldung/flink/connector/Consumers.java

@@ -9,23 +9,20 @@ import java.util.Properties;
 
 public class Consumers {
 
-public static FlinkKafkaConsumer011<String> createStringConsumerForTopic(
+    public static FlinkKafkaConsumer011<String> createStringConsumerForTopic(String topic, String kafkaAddress, String kafkaGroup) {
-  String topic, String kafkaAddress, String kafkaGroup ) {
+        Properties props = new Properties();
-    Properties props = new Properties();
+        props.setProperty("bootstrap.servers", kafkaAddress);
-    props.setProperty("bootstrap.servers", kafkaAddress);
+        props.setProperty("group.id", kafkaGroup);
-    props.setProperty("group.id",kafkaGroup);
+        FlinkKafkaConsumer011<String> consumer = new FlinkKafkaConsumer011<>(topic, new SimpleStringSchema(), props);
-    FlinkKafkaConsumer011<String> consumer =
-      new FlinkKafkaConsumer011<>(topic, new SimpleStringSchema(),props);
 
-    return consumer;
+        return consumer;
-}
+    }
 
-    public static FlinkKafkaConsumer011<InputMessage> createInputMessageConsumer(String topic, String kafkaAddress, String kafkaGroup ) {
+    public static FlinkKafkaConsumer011<InputMessage> createInputMessageConsumer(String topic, String kafkaAddress, String kafkaGroup) {
         Properties properties = new Properties();
         properties.setProperty("bootstrap.servers", kafkaAddress);
-        properties.setProperty("group.id",kafkaGroup);
+        properties.setProperty("group.id", kafkaGroup);
-        FlinkKafkaConsumer011<InputMessage> consumer = new FlinkKafkaConsumer011<InputMessage>(
+        FlinkKafkaConsumer011<InputMessage> consumer = new FlinkKafkaConsumer011<InputMessage>(topic, new InputMessageDeserializationSchema(), properties);
-                topic, new InputMessageDeserializationSchema(),properties);
 
         return consumer;
     }

apache-kafka/src/main/java/com/baeldung/flink/model/InputMessage.java

@@ -18,6 +18,7 @@ public class InputMessage {
     public String getSender() {
         return sender;
     }
+
     public void setSender(String sender) {
         this.sender = sender;
     }
@@ -55,12 +56,14 @@ public class InputMessage {
 
     @Override
     public boolean equals(Object o) {
-        if (this == o) return true;
+        if (this == o)
-        if (o == null || getClass() != o.getClass()) return false;
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
         InputMessage message1 = (InputMessage) o;
-        return Objects.equal(sender, message1.sender) &&
+        return Objects.equal(sender, message1.sender) && 
-                Objects.equal(recipient, message1.recipient) &&
+                Objects.equal(recipient, message1.recipient) && 
-                Objects.equal(sentAt, message1.sentAt) &&
+                Objects.equal(sentAt, message1.sentAt) && 
                 Objects.equal(message, message1.message);
     }
 

apache-kafka/src/main/java/com/baeldung/flink/operator/BackupAggregator.java

@@ -0,0 +1,34 @@
+package com.baeldung.flink.operator;
+
+import com.baeldung.flink.model.Backup;
+import com.baeldung.flink.model.InputMessage;
+import org.apache.flink.api.common.functions.AggregateFunction;
+
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.List;
+
+public class BackupAggregator implements AggregateFunction<InputMessage, List<InputMessage>, Backup> {
+    @Override
+    public List<InputMessage> createAccumulator() {
+        return new ArrayList<>();
+    }
+
+    @Override
+    public List<InputMessage> add(InputMessage inputMessage, List<InputMessage> inputMessages) {
+        inputMessages.add(inputMessage);
+        return inputMessages;
+    }
+
+    @Override
+    public Backup getResult(List<InputMessage> inputMessages) {
+        Backup backup = new Backup(inputMessages, LocalDateTime.now());
+        return backup;
+    }
+
+    @Override
+    public List<InputMessage> merge(List<InputMessage> inputMessages, List<InputMessage> acc1) {
+        inputMessages.addAll(acc1);
+        return inputMessages;
+    }
+}

apache-kafka/src/main/java/com/baeldung/flink/operator/InputMessageTimestampAssigner.java

@@ -12,7 +12,9 @@ public class InputMessageTimestampAssigner implements AssignerWithPunctuatedWate
     @Override
     public long extractTimestamp(InputMessage element, long previousElementTimestamp) {
         ZoneId zoneId = ZoneId.systemDefault();
-        return element.getSentAt().atZone(zoneId).toEpochSecond() * 1000;
+        return element.getSentAt()
+            .atZone(zoneId)
+            .toEpochSecond() * 1000;
     }
 
     @Nullable

apache-kafka/src/main/java/com/baeldung/flink/schema/BackupSerializationSchema.java

@@ -9,8 +9,7 @@ import org.apache.flink.api.common.serialization.SerializationSchema;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class BackupSerializationSchema
+public class BackupSerializationSchema implements SerializationSchema<Backup> {
-  implements SerializationSchema<Backup> {
 
     static ObjectMapper objectMapper = new ObjectMapper().registerModule(new JavaTimeModule());
 
@@ -18,7 +17,7 @@ public class BackupSerializationSchema
 
     @Override
     public byte[] serialize(Backup backupMessage) {
-        if(objectMapper == null) {
+        if (objectMapper == null) {
             objectMapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);
             objectMapper = new ObjectMapper().registerModule(new JavaTimeModule());
         }

apache-kafka/src/main/java/com/baeldung/flink/schema/InputMessageDeserializationSchema.java

@@ -8,12 +8,10 @@ import org.apache.flink.api.common.typeinfo.TypeInformation;
 
 import java.io.IOException;
 
-public class InputMessageDeserializationSchema implements
+public class InputMessageDeserializationSchema implements DeserializationSchema<InputMessage> {
-      DeserializationSchema<InputMessage> {
 
     static ObjectMapper objectMapper = new ObjectMapper().registerModule(new JavaTimeModule());
 
-
     @Override
     public InputMessage deserialize(byte[] bytes) throws IOException {
 

apache-kafka/src/main/java/com/baeldung/kafka/admin/KafkaTopicApplication.java

@@ -0,0 +1,83 @@
+package com.baeldung.kafka.admin;
+
+import org.apache.kafka.clients.admin.Admin;
+import org.apache.kafka.clients.admin.AdminClientConfig;
+import org.apache.kafka.clients.admin.CreateTopicsOptions;
+import org.apache.kafka.clients.admin.CreateTopicsResult;
+import org.apache.kafka.clients.admin.NewTopic;
+import org.apache.kafka.common.KafkaFuture;
+import org.apache.kafka.common.config.TopicConfig;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Properties;
+
+public class KafkaTopicApplication {
+
+    private final Properties properties;
+
+    public KafkaTopicApplication(Properties properties) {
+        this.properties = properties;
+    }
+
+    public void createTopic(String topicName) throws Exception {
+        try (Admin admin = Admin.create(properties)) {
+            int partitions = 1;
+            short replicationFactor = 1;
+            NewTopic newTopic = new NewTopic(topicName, partitions, replicationFactor);
+
+            CreateTopicsResult result = admin.createTopics(Collections.singleton(newTopic));
+
+            // get the async result for the new topic creation
+            KafkaFuture<Void> future = result.values()
+                .get(topicName);
+
+            // call get() to block until topic creation has completed or failed
+            future.get();
+        }
+    }
+
+    public void createTopicWithOptions(String topicName) throws Exception {
+        Properties props = new Properties();
+        props.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
+
+        try (Admin admin = Admin.create(props)) {
+            int partitions = 1;
+            short replicationFactor = 1;
+            NewTopic newTopic = new NewTopic(topicName, partitions, replicationFactor);
+
+            CreateTopicsOptions topicOptions = new CreateTopicsOptions().validateOnly(true)
+                .retryOnQuotaViolation(true);
+
+            CreateTopicsResult result = admin.createTopics(Collections.singleton(newTopic), topicOptions);
+
+            KafkaFuture<Void> future = result.values()
+                .get(topicName);
+            future.get();
+        }
+    }
+
+    public void createCompactedTopicWithCompression(String topicName) throws Exception {
+        Properties props = new Properties();
+        props.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
+
+        try (Admin admin = Admin.create(props)) {
+            int partitions = 1;
+            short replicationFactor = 1;
+
+            // Create a compacted topic with 'lz4' compression codec
+            Map<String, String> newTopicConfig = new HashMap<>();
+            newTopicConfig.put(TopicConfig.CLEANUP_POLICY_CONFIG, TopicConfig.CLEANUP_POLICY_COMPACT);
+            newTopicConfig.put(TopicConfig.COMPRESSION_TYPE_CONFIG, "lz4");
+            NewTopic newTopic = new NewTopic(topicName, partitions, replicationFactor).configs(newTopicConfig);
+
+            CreateTopicsResult result = admin.createTopics(Collections.singleton(newTopic));
+
+            KafkaFuture<Void> future = result.values()
+                .get(topicName);
+            future.get();
+        }
+    }
+
+}

apache-kafka/src/main/java/com/baeldung/kafka/consumer/CountryPopulationConsumer.java

@@ -19,9 +19,7 @@ public class CountryPopulationConsumer {
     private java.util.function.Consumer<Throwable> exceptionConsumer;
     private java.util.function.Consumer<CountryPopulation> countryPopulationConsumer;
 
-    public CountryPopulationConsumer(
+    public CountryPopulationConsumer(Consumer<String, Integer> consumer, java.util.function.Consumer<Throwable> exceptionConsumer, java.util.function.Consumer<CountryPopulation> countryPopulationConsumer) {
-            Consumer<String, Integer> consumer, java.util.function.Consumer<Throwable> exceptionConsumer,
-            java.util.function.Consumer<CountryPopulation> countryPopulationConsumer) {
         this.consumer = consumer;
         this.exceptionConsumer = exceptionConsumer;
         this.countryPopulationConsumer = countryPopulationConsumer;

apache-kafka/src/main/java/com/baeldung/kafka/dto/MessageDto.java

@@ -0,0 +1,15 @@
+package com.baeldung.kafka.dto;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+@Builder
+public class MessageDto {
+    private String message;
+    private String version;
+}

apache-kafka/src/main/java/com/baeldung/kafka/exactlyonce/TransactionalMessageProducer.java

@@ -1,4 +1,4 @@
-package com.baeldung.kafka;
+package com.baeldung.kafka.exactlyonce;
 
 import org.apache.kafka.clients.producer.KafkaProducer;
 import org.apache.kafka.clients.producer.ProducerRecord;
@@ -24,16 +24,16 @@ public class TransactionalMessageProducer {
 
         producer.initTransactions();
 
-        try{
+        try {
 
             producer.beginTransaction();
 
-            Stream.of(DATA_MESSAGE_1, DATA_MESSAGE_2).forEach(s -> producer.send(
+            Stream.of(DATA_MESSAGE_1, DATA_MESSAGE_2)
-                    new ProducerRecord<String, String>("input", null, s)));
+                .forEach(s -> producer.send(new ProducerRecord<String, String>("input", null, s)));
 
             producer.commitTransaction();
 
-        }catch (KafkaException e){
+        } catch (KafkaException e) {
 
             producer.abortTransaction();
 

apache-kafka/src/main/java/com/baeldung/kafka/exactlyonce/TransactionalWordCount.java

@@ -1,4 +1,4 @@
-package com.baeldung.kafka;
+package com.baeldung.kafka.exactlyonce;
 
 import org.apache.kafka.clients.consumer.ConsumerRecord;
 import org.apache.kafka.clients.consumer.ConsumerRecords;
@@ -43,10 +43,11 @@ public class TransactionalWordCount {
                 ConsumerRecords<String, String> records = consumer.poll(ofSeconds(60));
 
                 Map<String, Integer> wordCountMap = records.records(new TopicPartition(INPUT_TOPIC, 0))
-                        .stream()
+                    .stream()
-                        .flatMap(record -> Stream.of(record.value().split(" ")))
+                    .flatMap(record -> Stream.of(record.value()
-                        .map(word -> Tuple.of(word, 1))
+                        .split(" ")))
-                        .collect(Collectors.toMap(tuple -> tuple.getKey(), t1 -> t1.getValue(), (v1, v2) -> v1 + v2));
+                    .map(word -> Tuple.of(word, 1))
+                    .collect(Collectors.toMap(tuple -> tuple.getKey(), t1 -> t1.getValue(), (v1, v2) -> v1 + v2));
 
                 producer.beginTransaction();
 
@@ -56,7 +57,8 @@ public class TransactionalWordCount {
 
                 for (TopicPartition partition : records.partitions()) {
                     List<ConsumerRecord<String, String>> partitionedRecords = records.records(partition);
-                    long offset = partitionedRecords.get(partitionedRecords.size() - 1).offset();
+                    long offset = partitionedRecords.get(partitionedRecords.size() - 1)
+                        .offset();
 
                     offsetsToCommit.put(partition, new OffsetAndMetadata(offset + 1));
                 }
@@ -72,7 +74,6 @@ public class TransactionalWordCount {
 
         }
 
-
     }
 
     private static KafkaConsumer<String, String> createKafkaConsumer() {

apache-kafka/src/main/java/com/baeldung/kafka/exactlyonce/Tuple.java

@@ -1,4 +1,4 @@
-package com.baeldung.kafka;
+package com.baeldung.kafka.exactlyonce;
 
 public class Tuple {
 
@@ -10,8 +10,8 @@ public class Tuple {
         this.value = value;
     }
 
-    public static Tuple of(String key, Integer value){
+    public static Tuple of(String key, Integer value) {
-        return new Tuple(key,value);
+        return new Tuple(key, value);
     }
 
     public String getKey() {

apache-kafka/src/main/java/com/baeldung/kafka/producer/KafkaProducer.java

@@ -15,8 +15,7 @@ public class KafkaProducer {
     }
 
     public Future<RecordMetadata> send(String key, String value) {
-        ProducerRecord record = new ProducerRecord("topic_sports_news",
+        ProducerRecord record = new ProducerRecord("topic_sports_news", key, value);
-                key, value);
         return producer.send(record);
     }
 
@@ -36,5 +35,4 @@ public class KafkaProducer {
         producer.commitTransaction();
     }
 
-
 }

apache-kafka/src/main/java/com/baeldung/kafka/serdes/CustomDeserializer.java

@@ -0,0 +1,35 @@
+package com.baeldung.kafka.serdes;
+
+import com.baeldung.kafka.dto.MessageDto;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.kafka.common.errors.SerializationException;
+import org.apache.kafka.common.serialization.Deserializer;
+
+import java.util.Map;
+
+public class CustomDeserializer implements Deserializer<MessageDto> {
+
+    private ObjectMapper objectMapper = new ObjectMapper();
+
+    @Override
+    public void configure(Map<String, ?> configs, boolean isKey) {
+    }
+
+    @Override
+    public MessageDto deserialize(String topic, byte[] data) {
+        try {
+            if (data == null){
+                System.out.println("Null received at deserializing");
+                return null;
+            }
+            System.out.println("Deserializing...");
+            return objectMapper.readValue(new String(data, "UTF-8"), MessageDto.class);
+        } catch (Exception e) {
+            throw new SerializationException("Error when deserializing byte[] to MessageDto");
+        }
+    }
+
+    @Override
+    public void close() {
+    }
+}

apache-kafka/src/main/java/com/baeldung/kafka/serdes/CustomSerializer.java

@@ -0,0 +1,34 @@
+package com.baeldung.kafka.serdes;
+
+import com.baeldung.kafka.dto.MessageDto;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.kafka.common.errors.SerializationException;
+import org.apache.kafka.common.serialization.Serializer;
+
+import java.util.Map;
+
+public class CustomSerializer implements Serializer<MessageDto> {
+    private final ObjectMapper objectMapper = new ObjectMapper();
+
+    @Override
+    public void configure(Map<String, ?> configs, boolean isKey) {
+    }
+
+    @Override
+    public byte[] serialize(String topic, MessageDto data) {
+        try {
+            if (data == null){
+                System.out.println("Null received at serializing");
+                return null;
+            }
+            System.out.println("Serializing...");
+            return objectMapper.writeValueAsBytes(data);
+        } catch (Exception e) {
+            throw new SerializationException("Error when serializing MessageDto to byte[]");
+        }
+    }
+
+    @Override
+    public void close() {
+    }
+}

apache-kafka/src/test/java/com/baeldung/kafka/admin/KafkaTopicApplicationLiveTest.java

@@ -0,0 +1,42 @@
+package com.baeldung.kafka.admin;
+
+import org.apache.kafka.clients.admin.AdminClientConfig;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+import java.util.Properties;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+// This live test needs a running Docker instance so that a kafka container can be created 
+
+@Testcontainers
+class KafkaTopicApplicationLiveTest {
+
+    @Container
+    private static final KafkaContainer KAFKA_CONTAINER = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:5.4.3"));
+
+    private KafkaTopicApplication kafkaTopicApplication;
+
+    @BeforeEach
+    void setup() {
+        Properties properties = new Properties();
+        properties.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        kafkaTopicApplication = new KafkaTopicApplication(properties);
+    }
+
+    @Test
+    void givenTopicName_whenCreateNewTopic_thenTopicIsCreated() throws Exception {
+        kafkaTopicApplication.createTopic("test-topic");
+
+        String topicCommand = "/usr/bin/kafka-topics --bootstrap-server=localhost:9092 --list";
+        String stdout = KAFKA_CONTAINER.execInContainer("/bin/sh", "-c", topicCommand)
+          .getStdout();
+
+        assertThat(stdout).contains("test-topic");
+    }
+}

apache-kafka/src/test/java/com/baeldung/kafka/serdes/KafkaSerDesLiveTest.java

@@ -0,0 +1,94 @@
+package com.baeldung.kafka.serdes;
+
+import com.baeldung.kafka.dto.MessageDto;
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.junit.Before;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.utility.DockerImageName;
+
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.Properties;
+import java.util.concurrent.atomic.AtomicReference;
+
+import static org.junit.Assert.assertEquals;
+
+// This live test needs a Docker instance running so that kafka container can be created
+
+public class KafkaSerDesLiveTest {
+    private static final String CONSUMER_APP_ID = "consumer_id";
+    private static final String CONSUMER_GROUP_ID = "group_id";
+
+    @ClassRule
+    public static KafkaContainer kafka = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:5.4.3"));
+    private final String TOPIC = "mytopic";
+
+    private static KafkaConsumer<String, MessageDto> createKafkaConsumer() {
+
+        Properties props = new Properties();
+        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, kafka.getBootstrapServers());
+        props.put(ConsumerConfig.CLIENT_ID_CONFIG, CONSUMER_APP_ID);
+        props.put(ConsumerConfig.GROUP_ID_CONFIG, CONSUMER_GROUP_ID);
+        props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
+        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, "com.baeldung.kafka.serdes.CustomDeserializer");
+
+        return new KafkaConsumer<>(props);
+
+    }
+
+    private static KafkaProducer<String, MessageDto> createKafkaProducer() {
+
+        Properties props = new Properties();
+        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, kafka.getBootstrapServers());
+        props.put(ProducerConfig.CLIENT_ID_CONFIG, CONSUMER_APP_ID);
+        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer");
+        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, "com.baeldung.kafka.serdes.CustomSerializer");
+
+        return new KafkaProducer(props);
+
+    }
+
+    @Before
+    public void setUp() {
+    }
+
+    @Test
+    public void givenKafkaClientShouldSerializeAndDeserialize() throws InterruptedException {
+
+        MessageDto msgProd = MessageDto.builder().message("test").version("1.0").build();
+
+        KafkaProducer<String, MessageDto> producer = createKafkaProducer();
+        producer.send(new ProducerRecord<String, MessageDto>(TOPIC, "1", msgProd));
+        System.out.println("Message sent " + msgProd);
+        producer.close();
+
+        Thread.sleep(2000);
+
+        AtomicReference<MessageDto> msgCons = new AtomicReference<>();
+
+        KafkaConsumer<String, MessageDto> consumer = createKafkaConsumer();
+        consumer.subscribe(Arrays.asList(TOPIC));
+
+        ConsumerRecords<String, MessageDto> records = consumer.poll(Duration.ofSeconds(1));
+        records.forEach(record -> {
+            msgCons.set(record.value());
+            System.out.println("Message received " + record.value());
+        });
+
+        consumer.close();
+
+        assertEquals(msgProd, msgCons.get());
+
+    }
+
+}
+
+

apache-kafka/src/test/java/com/baeldung/kafka/streamsvsconsumer/KafkaStreamsLiveTest.java

@@ -0,0 +1,281 @@
+package com.baeldung.kafka.streamsvsconsumer;
+
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.apache.kafka.common.serialization.Serde;
+import org.apache.kafka.common.serialization.Serdes;
+import org.apache.kafka.common.utils.Bytes;
+import org.apache.kafka.streams.KafkaStreams;
+import org.apache.kafka.streams.KeyValue;
+import org.apache.kafka.streams.StoreQueryParameters;
+import org.apache.kafka.streams.StreamsBuilder;
+import org.apache.kafka.streams.StreamsConfig;
+import org.apache.kafka.streams.Topology;
+import org.apache.kafka.streams.kstream.Consumed;
+import org.apache.kafka.streams.kstream.Grouped;
+import org.apache.kafka.streams.kstream.JoinWindows;
+import org.apache.kafka.streams.kstream.KGroupedStream;
+import org.apache.kafka.streams.kstream.KGroupedTable;
+import org.apache.kafka.streams.kstream.KStream;
+import org.apache.kafka.streams.kstream.KTable;
+import org.apache.kafka.streams.kstream.Materialized;
+import org.apache.kafka.streams.kstream.Produced;
+import org.apache.kafka.streams.kstream.TimeWindows;
+import org.apache.kafka.streams.state.KeyValueIterator;
+import org.apache.kafka.streams.state.KeyValueStore;
+import org.apache.kafka.streams.state.QueryableStoreTypes;
+import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
+import org.apache.kafka.streams.state.StoreBuilder;
+import org.apache.kafka.streams.state.Stores;
+import org.apache.kafka.streams.state.WindowStore;
+import org.junit.Before;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.utility.DockerImageName;
+
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.Locale;
+import java.util.Properties;
+
+import static org.apache.kafka.clients.consumer.ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG;
+import static org.apache.kafka.clients.producer.ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG;
+import static org.apache.kafka.clients.producer.ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG;
+
+// This live test needs a Docker instance running so that kafka container can be created
+
+public class KafkaStreamsLiveTest {
+    private final String LEFT_TOPIC = "left-stream-topic";
+    private final String RIGHT_TOPIC = "right-stream-topic";
+    private final String LEFT_RIGHT_TOPIC = "left-right-stream-topic";
+
+    private KafkaProducer<String, String> producer = createKafkaProducer();
+    private Properties streamsConfiguration = new Properties();
+
+    static final String TEXT_LINES_TOPIC = "TextLinesTopic";
+
+    private final String TEXT_EXAMPLE_1 = "test test and test";
+    private final String TEXT_EXAMPLE_2 = "test filter filter this sentence";
+
+    @ClassRule
+    public static KafkaContainer kafka = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:5.4.3"));
+
+    @Before
+    public void setUp() {
+        streamsConfiguration.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, kafka.getBootstrapServers());
+        streamsConfiguration.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
+        streamsConfiguration.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
+        streamsConfiguration.put(StreamsConfig.COMMIT_INTERVAL_MS_CONFIG, 1000);
+        streamsConfiguration.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+    }
+
+    @Test
+    public void shouldTestKafkaTableLatestWord() throws InterruptedException {
+        String inputTopic = "topicTable";
+
+        final StreamsBuilder builder = new StreamsBuilder();
+
+        KTable<String, String> textLinesTable = builder.table(inputTopic,
+            Consumed.with(Serdes.String(), Serdes.String()));
+
+        textLinesTable.toStream().foreach((word, count) -> System.out.println("Latest word: " + word + " -> " + count));
+
+        final Topology topology = builder.build();
+        streamsConfiguration.put(StreamsConfig.APPLICATION_ID_CONFIG, "latest-word-id");
+        KafkaStreams streams = new KafkaStreams(topology, streamsConfiguration);
+
+        streams.cleanUp();
+        streams.start();
+        producer.send(new ProducerRecord<String, String>(inputTopic, "1", TEXT_EXAMPLE_1));
+        producer.send(new ProducerRecord<String, String>(inputTopic, "2", TEXT_EXAMPLE_2));
+
+        Thread.sleep(2000);
+        streams.close();
+    }
+
+    @Test
+    public void shouldTestWordCountKafkaStreams() throws InterruptedException {
+        String wordCountTopic = "wordCountTopic";
+
+        final StreamsBuilder builder = new StreamsBuilder();
+        KStream<String, String> textLines = builder.stream(wordCountTopic,
+          Consumed.with(Serdes.String(), Serdes.String()));
+
+        KTable<String, Long> wordCounts = textLines
+          .flatMapValues(value -> Arrays.asList(value.toLowerCase(Locale.ROOT)
+            .split("\\W+")))
+          .groupBy((key, word) -> word)
+          .count(Materialized.<String, Long, KeyValueStore<Bytes, byte[]>> as("counts-store"));
+
+        wordCounts.toStream().foreach((word, count) -> System.out.println("Word: " + word + " -> " + count));
+
+        wordCounts.toStream().to("outputTopic",
+          Produced.with(Serdes.String(), Serdes.Long()));
+
+        streamsConfiguration.put(StreamsConfig.APPLICATION_ID_CONFIG, "wordcount-stream-table-id");
+        final Topology topology = builder.build();
+        KafkaStreams streams = new KafkaStreams(topology, streamsConfiguration);
+
+        streams.cleanUp();
+        streams.start();
+
+        producer.send(new ProducerRecord<String, String>(wordCountTopic, "1", TEXT_EXAMPLE_1));
+        producer.send(new ProducerRecord<String, String>(wordCountTopic, "2", TEXT_EXAMPLE_2));
+
+        Thread.sleep(2000);
+        streams.close();
+    }
+
+    // Filter, map
+    @Test
+    public void shouldTestStatelessTransformations() throws InterruptedException {
+        String wordCountTopic = "wordCountTopic";
+
+        //when
+        final StreamsBuilder builder = new StreamsBuilder();
+        KStream<String, String> textLines = builder.stream(wordCountTopic,
+          Consumed.with(Serdes.String(), Serdes.String()));
+
+        final KStream<String, String> textLinesUpperCase =
+          textLines
+            .map((key, value) -> KeyValue.pair(value, value.toUpperCase()))
+            .filter((key, value) -> value.contains("FILTER"));
+
+        KTable<String, Long> wordCounts = textLinesUpperCase
+          .flatMapValues(value -> Arrays.asList(value.split("\\W+")))
+          .groupBy((key, word) -> word)
+          .count(Materialized.<String, Long, KeyValueStore<Bytes, byte[]>> as("counts-store"));
+
+        wordCounts.toStream().foreach((word, count) -> System.out.println("Word: " + word + " -> " + count));
+
+        streamsConfiguration.put(StreamsConfig.APPLICATION_ID_CONFIG, "wordcount-filter-map-id");
+        final Topology topology = builder.build();
+        KafkaStreams streams = new KafkaStreams(topology, streamsConfiguration);
+
+        streams.cleanUp();
+        streams.start();
+
+        producer.send(new ProducerRecord<String, String>(wordCountTopic, "1", TEXT_EXAMPLE_1));
+        producer.send(new ProducerRecord<String, String>(wordCountTopic, "2", TEXT_EXAMPLE_2));
+
+        Thread.sleep(2000);
+        streams.close();
+
+    }
+
+    @Test
+    public void shouldTestAggregationStatefulTransformations() throws InterruptedException {
+        String aggregationTopic = "aggregationTopic";
+
+        final StreamsBuilder builder = new StreamsBuilder();
+        final KStream<byte[], String> input = builder.stream(aggregationTopic,
+          Consumed.with(Serdes.ByteArray(), Serdes.String()));
+        final KTable<String, Long> aggregated = input
+          .groupBy((key, value) -> (value != null && value.length() > 0) ? value.substring(0, 2).toLowerCase() : "",
+            Grouped.with(Serdes.String(), Serdes.String()))
+          .aggregate(() -> 0L, (aggKey, newValue, aggValue) -> aggValue + newValue.length(),
+            Materialized.with(Serdes.String(), Serdes.Long()));
+
+        aggregated.toStream().foreach((word, count) -> System.out.println("Word: " + word + " -> " + count));
+
+        streamsConfiguration.put(StreamsConfig.APPLICATION_ID_CONFIG, "aggregation-id");
+        final Topology topology = builder.build();
+        KafkaStreams streams = new KafkaStreams(topology, streamsConfiguration);
+
+        streams.cleanUp();
+        streams.start();
+
+        producer.send(new ProducerRecord<String, String>(aggregationTopic, "1", "one"));
+        producer.send(new ProducerRecord<String, String>(aggregationTopic, "2", "two"));
+        producer.send(new ProducerRecord<String, String>(aggregationTopic, "3", "three"));
+        producer.send(new ProducerRecord<String, String>(aggregationTopic, "4", "four"));
+        producer.send(new ProducerRecord<String, String>(aggregationTopic, "5", "five"));
+
+        Thread.sleep(5000);
+        streams.close();
+
+    }
+
+    @Test
+    public void shouldTestWindowingJoinStatefulTransformations() throws InterruptedException {
+        final StreamsBuilder builder = new StreamsBuilder();
+
+       KStream<String, String> leftSource = builder.stream(LEFT_TOPIC);
+       KStream<String, String> rightSource = builder.stream(RIGHT_TOPIC);
+
+        KStream<String, String> leftRightSource = leftSource.outerJoin(rightSource,
+         (leftValue, rightValue) -> "left=" + leftValue + ", right=" + rightValue,
+         JoinWindows.of(Duration.ofSeconds(5)))
+           .groupByKey()
+           .reduce(((key, lastValue) -> lastValue))
+           .toStream();
+
+        leftRightSource.foreach((key, value) -> System.out.println("(key= " + key + ") -> (" + value + ")"));
+
+        final Topology topology = builder.build();
+        streamsConfiguration.put(StreamsConfig.APPLICATION_ID_CONFIG, "windowing-join-id");
+        KafkaStreams streams = new KafkaStreams(topology, streamsConfiguration);
+
+        streams.cleanUp();
+        streams.start();
+
+        producer.send(new ProducerRecord<String, String>(LEFT_TOPIC, "1", "left"));
+        producer.send(new ProducerRecord<String, String>(RIGHT_TOPIC, "2", "right"));
+
+        Thread.sleep(2000);
+        streams.close();
+    }
+
+    @Test
+    public void shouldTestWordCountWithInteractiveQueries() throws InterruptedException {
+
+        final Serde<String> stringSerde = Serdes.String();
+        final StreamsBuilder builder = new StreamsBuilder();
+        final KStream<String, String>
+          textLines = builder.stream(TEXT_LINES_TOPIC, Consumed.with(Serdes.String(), Serdes.String()));
+
+        final KGroupedStream<String, String> groupedByWord = textLines
+          .flatMapValues(value -> Arrays.asList(value.toLowerCase().split("\\W+")))
+          .groupBy((key, word) -> word, Grouped.with(stringSerde, stringSerde));
+
+        groupedByWord.count(Materialized.<String, Long, KeyValueStore<Bytes, byte[]>>as("WordCountsStore")
+          .withValueSerde(Serdes.Long()));
+
+        streamsConfiguration.put(StreamsConfig.APPLICATION_ID_CONFIG, "wordcount-interactive-queries");
+
+        final KafkaStreams streams = new KafkaStreams(builder.build(), streamsConfiguration);
+        streams.cleanUp();
+        streams.start();
+
+        producer.send(new ProducerRecord<String, String>(TEXT_LINES_TOPIC, "1", TEXT_EXAMPLE_1));
+        producer.send(new ProducerRecord<String, String>(TEXT_LINES_TOPIC, "2", TEXT_EXAMPLE_2));
+
+        Thread.sleep(2000);
+        ReadOnlyKeyValueStore<String, Long> keyValueStore =
+          streams.store(StoreQueryParameters.fromNameAndType(
+            "WordCountsStore", QueryableStoreTypes.keyValueStore()));
+
+        KeyValueIterator<String, Long> range = keyValueStore.all();
+        while (range.hasNext()) {
+            KeyValue<String, Long> next = range.next();
+            System.out.println("Count for " + next.key + ": " + next.value);
+        }
+
+        streams.close();
+    }
+
+    private static KafkaProducer<String, String> createKafkaProducer() {
+
+        Properties props = new Properties();
+        props.put(BOOTSTRAP_SERVERS_CONFIG, kafka.getBootstrapServers());
+        props.put(KEY_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer");
+        props.put(VALUE_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer");
+
+        return new KafkaProducer(props);
+
+    }
+}
+
+

apache-kafka/src/test/java/com/baeldung/kafkastreams/KafkaStreamsLiveTest.java

@@ -1,7 +1,14 @@
 package com.baeldung.kafkastreams;
 
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.Properties;
+import java.util.regex.Pattern;
+
 import org.apache.kafka.clients.consumer.ConsumerConfig;
-import org.apache.kafka.common.serialization.Serde;
 import org.apache.kafka.common.serialization.Serdes;
 import org.apache.kafka.streams.KafkaStreams;
 import org.apache.kafka.streams.StreamsBuilder;
@@ -10,16 +17,12 @@ import org.apache.kafka.streams.Topology;
 import org.apache.kafka.streams.kstream.KStream;
 import org.apache.kafka.streams.kstream.KTable;
 import org.apache.kafka.streams.kstream.Produced;
-import org.apache.kafka.test.TestUtils;
 import org.junit.Ignore;
 import org.junit.Test;
 
-import java.util.Arrays;
-import java.util.Properties;
-import java.util.regex.Pattern;
-
 public class KafkaStreamsLiveTest {
     private String bootstrapServers = "localhost:9092";
+    private Path stateDirectory;
 
     @Test
     @Ignore("it needs to have kafka broker running on local")
@@ -30,28 +33,43 @@ public class KafkaStreamsLiveTest {
         Properties streamsConfiguration = new Properties();
         streamsConfiguration.put(StreamsConfig.APPLICATION_ID_CONFIG, "wordcount-live-test");
         streamsConfiguration.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
-        streamsConfiguration.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
+        streamsConfiguration.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String()
-        streamsConfiguration.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
+            .getClass()
+            .getName());
+        streamsConfiguration.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String()
+            .getClass()
+            .getName());
         streamsConfiguration.put(StreamsConfig.COMMIT_INTERVAL_MS_CONFIG, 1000);
         streamsConfiguration.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+        
         // Use a temporary directory for storing state, which will be automatically removed after the test.
-        streamsConfiguration.put(StreamsConfig.STATE_DIR_CONFIG, TestUtils.tempDirectory().getAbsolutePath());
+        try {
+            this.stateDirectory = Files.createTempDirectory("kafka-streams");
+            streamsConfiguration.put(StreamsConfig.STATE_DIR_CONFIG, this.stateDirectory.toAbsolutePath()
+                .toString());
+        } catch (final IOException e) {
+            throw new UncheckedIOException("Cannot create temporary directory", e);
+        }
 
         // when
-        StreamsBuilder builder = new StreamsBuilder();
+        final StreamsBuilder builder = new StreamsBuilder();
         KStream<String, String> textLines = builder.stream(inputTopic);
         Pattern pattern = Pattern.compile("\\W+", Pattern.UNICODE_CHARACTER_CLASS);
 
-        KTable<String, Long> wordCounts = textLines.flatMapValues(value -> Arrays.asList(pattern.split(value.toLowerCase()))).groupBy((key, word) -> word).count();
+        KTable<String, Long> wordCounts = textLines.flatMapValues(value -> Arrays.asList(pattern.split(value.toLowerCase())))
+            .groupBy((key, word) -> word)
+            .count();
 
-        textLines.foreach((word, count) -> System.out.println("word: " + word + " -> " + count));
+        wordCounts.toStream()
+            .foreach((word, count) -> System.out.println("word: " + word + " -> " + count));
 
         String outputTopic = "outputTopic";
-        final Serde<String> stringSerde = Serdes.String();
-        final Serde<String> longSerde = Serdes.String();
-        textLines.to(outputTopic, Produced.with(stringSerde,longSerde));
 
-        KafkaStreams streams = new KafkaStreams(new Topology(), streamsConfiguration);
+        wordCounts.toStream()
+            .to(outputTopic, Produced.with(Serdes.String(), Serdes.Long()));
+
+        final Topology topology = builder.build();
+        KafkaStreams streams = new KafkaStreams(topology, streamsConfiguration);
         streams.start();
 
         // then

apache-libraries/pom.xml

@@ -1,5 +1,6 @@
 <?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"
+<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <artifactId>apache-libraries</artifactId>
@@ -29,7 +30,6 @@
             <artifactId>avro-maven-plugin</artifactId>
             <version>${avro.version}</version>
         </dependency>
-
         <!-- beam -->
         <dependency>
             <groupId>org.apache.beam</groupId>
@@ -43,7 +43,6 @@
             <version>${beam.version}</version>
             <scope>runtime</scope>
         </dependency>
-
         <!-- bval -->
         <dependency>
             <groupId>org.apache.bval</groupId>
@@ -60,7 +59,6 @@
             <artifactId>bval-extras</artifactId>
             <version>${bval.version}</version>
         </dependency>
-
         <!-- meecrowave -->
         <dependency>
             <groupId>org.apache.meecrowave</groupId>
@@ -84,14 +82,12 @@
             <version>${meecrowave-junit.version}</version>
             <scope>test</scope>
         </dependency>
-        
         <!-- opennlp -->
         <dependency>
             <groupId>org.apache.opennlp</groupId>
             <artifactId>opennlp-tools</artifactId>
             <version>${opennlp.opennlp-tools.version}</version>
         </dependency>
-        
         <!-- pulsar -->
         <dependency>
             <groupId>org.apache.pulsar</groupId>
@@ -99,14 +95,12 @@
             <version>${pulsar-client.version}</version>
             <scope>compile</scope>
         </dependency>
-        
         <!-- zookeeper -->
         <dependency>
             <groupId>org.apache.zookeeper</groupId>
             <artifactId>zookeeper</artifactId>
             <version>${zookeeper.version}</version>
         </dependency>
-        
         <!-- curator -->
         <dependency>
             <groupId>org.apache.curator</groupId>
@@ -139,27 +133,29 @@
             <artifactId>jackson-databind</artifactId>
             <version>${jackson.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-annotations</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
         <dependency>
             <groupId>com.jayway.awaitility</groupId>
             <artifactId>awaitility</artifactId>
             <version>${avaitility.version}</version>
             <scope>test</scope>
         </dependency>
-        
         <!-- geode -->
         <dependency>
             <groupId>org.apache.geode</groupId>
             <artifactId>geode-core</artifactId>
             <version>${geode.core}</version>
         </dependency>
-        
         <!-- solr -->
         <dependency>
             <groupId>org.apache.solr</groupId>
             <artifactId>solr-solrj</artifactId>
             <version>${solr.solr-solrj.version}</version>
         </dependency>
-        
         <!-- common -->
         <dependency>
             <groupId>org.assertj</groupId>
@@ -171,7 +167,7 @@
 
     <build>
         <plugins>
-        <!-- avro -->
+            <!-- avro -->
             <plugin>
                 <groupId>org.apache.avro</groupId>
                 <artifactId>avro-maven-plugin</artifactId>
@@ -192,7 +188,6 @@
                     </execution>
                 </executions>
             </plugin>
-            
             <!-- meecrowave -->
             <plugin>
                 <groupId>org.apache.meecrowave</groupId>
@@ -206,7 +201,6 @@
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
         <avro.version>1.8.2</avro.version>
-        <slf4j.version>1.7.25</slf4j.version>
         <beam.version>2.19.0</beam.version>
         <assertj.version>3.9.0</assertj.version>
         <bval.version>1.1.2</bval.version>
@@ -225,4 +219,4 @@
         <solr.solr-solrj.version>6.4.0</solr.solr-solrj.version>
     </properties>
 
-</project>
+</project>

apache-libraries/src/main/resources/log4j2.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<Configuration status="WARN">
+    <Appenders>
+        <Console name="Console" target="SYSTEM_OUT">
+            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
+        </Console>
+    </Appenders>
+    <Loggers>
+        <Logger name="org.apache.meecrowave" level="warn">
+            <AppenderRef ref="Console"/>
+        </Logger>
+
+        <Root level="info">
+            <AppenderRef ref="Console"/>
+        </Root>
+    </Loggers>
+</Configuration>

apache-libraries/src/test/java/com/baeldung/apache/beam/intro/WordCountUnitTest.java

@@ -10,7 +10,6 @@ import com.baeldung.apache.beam.intro.WordCount;
 public class WordCountUnitTest {
     
     @Test
-    // @Ignore
     public void givenInputFile_whenWordCountRuns_thenJobFinishWithoutError() {
         boolean jobDone = WordCount.wordCount("src/test/resources/wordcount.txt", "target/output");
         assertTrue(jobDone);

apache-olingo/olingo2/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -40,7 +39,6 @@
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
         </dependency>
-
         <!-- Olingo 2 Dependencies -->
         <dependency>
             <groupId>org.apache.olingo</groupId>
@@ -85,4 +83,4 @@
         <olingo2.version>2.0.11</olingo2.version>
     </properties>
 
-</project>
+</project>

apache-olingo/olingo2/src/main/resources/application.yml

@@ -6,7 +6,12 @@ spring:
     application-path: /odata
     
   jpa:
+    defer-datasource-initialization: true
     show-sql: true
     open-in-view: false
     hibernate:
-      ddl-auto: update
+      ddl-auto: update
+
+  sql:
+    init:
+      mode: always

apache-poi/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -38,4 +37,4 @@
         <jexcel.version>1.0.6</jexcel.version>
     </properties>
 
-</project>
+</project>

apache-poi/src/main/java/com/baeldung/poi/excel/multilinetext/MultilineText.java

@@ -0,0 +1,18 @@
+package com.baeldung.poi.excel.multilinetext;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.CellStyle;
+import org.apache.poi.ss.usermodel.Row;
+
+public class MultilineText {
+    public void formatMultilineText(Cell cell, int cellNumber) {
+        cell.getRow()
+            .setHeightInPoints(cell.getSheet()
+                .getDefaultRowHeightInPoints() * 2);
+        CellStyle cellStyle = cell.getSheet()
+            .getWorkbook()
+            .createCellStyle();
+        cellStyle.setWrapText(true);
+        cell.setCellStyle(cellStyle);
+    }
+}

apache-poi/src/test/java/com/baeldung/poi/excel/multilinetext/MultilineTextUnitTest.java

@@ -0,0 +1,69 @@
+package com.baeldung.poi.excel.multilinetext;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.file.Paths;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.DataFormatter;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.junit.Before;
+import org.junit.Test;
+
+public class MultilineTextUnitTest {
+    private static String FILE_NAME = "com/baeldung/poi/excel/multilinetext/MultilineTextTest.xlsx";
+    private static final String NEW_FILE_NAME = "MultilineTextTest_output.xlsx";
+    private static final int STRING_ROW_INDEX = 1;
+    private static final int STRING_CELL_INDEX = 0;
+
+    private String fileLocation;
+
+    @Before
+    public void setup() throws IOException, URISyntaxException {
+        fileLocation = Paths.get(ClassLoader.getSystemResource(FILE_NAME)
+            .toURI())
+            .toString();
+    }
+
+    @Test
+    public void givenMultilineTextCell_whenFormated_thenMultilineTextVisible() throws IOException {
+        Workbook workbook = new XSSFWorkbook(fileLocation);
+        Sheet sheet = workbook.getSheetAt(0);
+        sheet.createRow(STRING_ROW_INDEX);
+        Row row = sheet.getRow(STRING_ROW_INDEX);
+        Cell cell = row.createCell(STRING_CELL_INDEX);
+
+        cell.setCellValue("Hello \n world!");
+        MultilineText multilineText = new MultilineText();
+        multilineText.formatMultilineText(cell, STRING_CELL_INDEX);
+
+        FileOutputStream outputStream = new FileOutputStream(NEW_FILE_NAME);
+        workbook.write(outputStream);
+        outputStream.close();
+
+        File file = new File(NEW_FILE_NAME);
+        FileInputStream fileInputStream = new FileInputStream(file);
+        Workbook testWorkbook = new XSSFWorkbook(fileInputStream);
+        assertTrue(row.getHeightInPoints() == testWorkbook.getSheetAt(0)
+            .getRow(STRING_ROW_INDEX)
+            .getHeightInPoints());
+        DataFormatter formatter = new DataFormatter();
+        assertEquals("Hello \n world!", formatter.formatCellValue(testWorkbook.getSheetAt(0)
+            .getRow(STRING_ROW_INDEX)
+            .getCell(STRING_CELL_INDEX)));
+        testWorkbook.close();
+        fileInputStream.close();
+        file.delete();
+
+        workbook.close();
+    }
+}

apache-rocketmq/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -26,4 +25,5 @@
         <geode.core>1.6.0</geode.core>
         <rocketmq.version>2.0.4</rocketmq.version>
     </properties>
-</project>
+
+</project>

apache-shiro/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -40,10 +39,6 @@
             <scope>runtime</scope>
         </dependency>
         <!-- spring-sec -->
-        <dependency>
-            <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-starter-web</artifactId>
-        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-security</artifactId>
@@ -55,4 +50,4 @@
         <log4j-version>1.2.17</log4j-version>
     </properties>
 
-</project>
+</project>

apache-spark/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -95,20 +94,20 @@
     <repositories>
         <repository>
             <id>SparkPackagesRepo</id>
-            <url>http://dl.bintray.com/spark-packages/maven</url>
+            <url>https://repos.spark-packages.org</url>
         </repository>
     </repositories>
 
     <properties>
-        <org.apache.spark.spark-core.version>2.3.0</org.apache.spark.spark-core.version>
+        <org.apache.spark.spark-core.version>2.4.8</org.apache.spark.spark-core.version>
-        <org.apache.spark.spark-sql.version>2.3.0</org.apache.spark.spark-sql.version>
+        <org.apache.spark.spark-sql.version>2.4.8</org.apache.spark.spark-sql.version>
-        <org.apache.spark.spark-streaming.version>2.3.0</org.apache.spark.spark-streaming.version>
+        <org.apache.spark.spark-streaming.version>2.4.8</org.apache.spark.spark-streaming.version>
-        <org.apache.spark.spark-mllib.version>2.3.0</org.apache.spark.spark-mllib.version>
+        <org.apache.spark.spark-mllib.version>2.4.8</org.apache.spark.spark-mllib.version>
-        <org.apache.spark.spark-graphx.version>2.3.0</org.apache.spark.spark-graphx.version>
+        <org.apache.spark.spark-graphx.version>2.4.8</org.apache.spark.spark-graphx.version>
-        <graphframes.version>0.7.0-spark2.4-s_2.11</graphframes.version>
+        <graphframes.version>0.8.1-spark3.0-s_2.12</graphframes.version>
-        <org.apache.spark.spark-streaming-kafka.version>2.3.0</org.apache.spark.spark-streaming-kafka.version>
+        <org.apache.spark.spark-streaming-kafka.version>2.4.8</org.apache.spark.spark-streaming-kafka.version>
-        <com.datastax.spark.spark-cassandra-connector.version>2.3.0</com.datastax.spark.spark-cassandra-connector.version>
+        <com.datastax.spark.spark-cassandra-connector.version>2.5.2</com.datastax.spark.spark-cassandra-connector.version>
-        <com.datastax.spark.spark-cassandra-connector-java.version>1.5.2</com.datastax.spark.spark-cassandra-connector-java.version>
+        <com.datastax.spark.spark-cassandra-connector-java.version>1.6.0-M1</com.datastax.spark.spark-cassandra-connector-java.version>
     </properties>
 
-</project>
+</project>

apache-spark/src/main/resources/log4j.properties

@@ -0,0 +1,42 @@
+#
+# 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.
+#
+
+# Set everything to be logged to the console
+log4j.rootCategory=WARN, console
+log4j.appender.console=org.apache.log4j.ConsoleAppender
+log4j.appender.console.target=System.err
+log4j.appender.console.layout=org.apache.log4j.PatternLayout
+log4j.appender.console.layout.ConversionPattern=%d{yy/MM/dd HH:mm:ss} %p %c{1}: %m%n
+
+# Set the default spark-shell log level to WARN. When running the spark-shell, the
+# log level for this class is used to overwrite the root logger's log level, so that
+# the user can have different defaults for the shell and regular Spark apps.
+log4j.logger.org.apache.spark.repl.Main=WARN
+
+# Settings to quiet third party logs that are too verbose
+log4j.logger.org.spark_project.jetty=WARN
+log4j.logger.org.spark_project.jetty.util.component.AbstractLifeCycle=ERROR
+log4j.logger.org.apache.spark.repl.SparkIMain$exprTyper=INFO
+log4j.logger.org.apache.spark.repl.SparkILoop$SparkILoopInterpreter=INFO
+
+# SPARK-9183: Settings to avoid annoying messages when looking up nonexistent UDFs in SparkSQL with Hive support
+log4j.logger.org.apache.hadoop.hive.metastore.RetryingHMSHandler=FATAL
+log4j.logger.org.apache.hadoop.hive.ql.exec.FunctionRegistry=ERROR
+
+# Parquet related logging
+log4j.logger.org.apache.parquet.CorruptStatistics=ERROR
+log4j.logger.parquet.CorruptStatistics=ERROR

apache-tapestry/pom.xml

@@ -1,8 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"
+    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 http://maven.apache.org/maven-v4_0_0.xsd">
-    xmlns="http://maven.apache.org/POM/4.0.0">
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung</groupId>
     <artifactId>apache-tapestry</artifactId>
@@ -12,45 +11,42 @@
 
     <dependencies>
         <!-- To set up an application with a database, change the artifactId below to tapestry-hibernate, 
-        and add a dependency on your JDBC driver. You'll also need to add Hibernate configuration files, such as hibernate.cfg.xml. -->
+            and add a dependency on your JDBC driver. You'll also need to add Hibernate configuration files, such 
+            as hibernate.cfg.xml. -->
         <dependency>
             <groupId>org.apache.tapestry</groupId>
             <artifactId>tapestry-core</artifactId>
             <version>${tapestry-release-version}</version>
         </dependency>
-
         <!-- Include the Log4j implementation for the SLF4J logging framework -->
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-log4j12</artifactId>
             <version>${slf4j-release-version}</version>
         </dependency>
-
         <dependency>
             <groupId>org.apache.tapestry</groupId>
             <artifactId>tapestry-webresources</artifactId>
             <version>${tapestry-release-version}</version>
         </dependency>
-
         <!-- Uncomment this to add support for file uploads: -->
-        <!-- <dependency> <groupId>org.apache.tapestry</groupId> <artifactId>tapestry-upload</artifactId> <version>${tapestry-release-version}</version> </dependency> -->
+        <!-- <dependency> <groupId>org.apache.tapestry</groupId> <artifactId>tapestry-upload</artifactId> 
-
+            <version>${tapestry-release-version}</version> </dependency> -->
-        <!-- A dependency on either JUnit or TestNG is required, or the surefire plugin (which runs the tests) will fail, preventing Maven from packaging the WAR. Tapestry includes 
+        <!-- A dependency on either JUnit or TestNG is required, or the surefire plugin (which runs the 
-            a large number of testing facilities designed for use with TestNG (http://testng.org/), so it's recommended. -->
+            tests) will fail, preventing Maven from packaging the WAR. Tapestry includes a large number of testing 
+            facilities designed for use with TestNG (http://testng.org/), so it's recommended. -->
         <dependency>
             <groupId>org.testng</groupId>
             <artifactId>testng</artifactId>
             <version>${testng-release-version}</version>
             <scope>test</scope>
         </dependency>
-
         <dependency>
             <groupId>org.apache.tapestry</groupId>
             <artifactId>tapestry-test</artifactId>
             <version>${tapestry-release-version}</version>
             <scope>test</scope>
         </dependency>
-
         <!-- Provided by the servlet container, but sometimes referenced in the application code. -->
         <dependency>
             <groupId>javax.servlet</groupId>
@@ -58,7 +54,6 @@
             <version>${servlet-api-release-version}</version>
             <scope>provided</scope>
         </dependency>
-
         <!-- Provide dependency to the Tapestry javadoc taglet which replaces the Maven component report -->
         <dependency>
             <groupId>org.apache.tapestry</groupId>
@@ -81,7 +76,6 @@
                     <optimize>true</optimize>
                 </configuration>
             </plugin>
-
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-surefire-plugin</artifactId>
@@ -92,7 +86,6 @@
                     </systemPropertyVariables>
                 </configuration>
             </plugin>
-
             <!-- Run the application using "mvn jetty:run" -->
             <plugin>
                 <groupId>org.mortbay.jetty</groupId>
@@ -101,7 +94,8 @@
                 <configuration>
                     <!-- Log to the console. -->
                     <requestLog implementation="org.mortbay.jetty.NCSARequestLog">
-                        <!-- This doesn't do anything for Jetty, but is a workaround for a Maven bug that prevents the requestLog from being set. -->
+                        <!-- This doesn't do anything for Jetty, but is a workaround for a Maven bug 
+                            that prevents the requestLog from being set. -->
                         <append>true</append>
                     </requestLog>
                     <systemProperties>
@@ -115,15 +109,13 @@
         </plugins>
     </build>
 
-    <reporting />
-
     <repositories>
         <repository>
             <id>jboss</id>
             <url>http://repository.jboss.org/nexus/content/groups/public/</url>
         </repository>
-
+        <!-- This repository is only needed when the Tapestry version is a preview release, rather than 
-        <!-- This repository is only needed when the Tapestry version is a preview release, rather than a final release. -->
+            a final release. -->
         <repository>
             <id>apache-staging</id>
             <url>https://repository.apache.org/content/groups/staging/</url>
@@ -142,4 +134,4 @@
         <slf4j-release-version>1.7.19</slf4j-release-version>
     </properties>
 
-</project>
+</project>

apache-thrift/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -27,11 +26,10 @@
                 </exclusion>
             </exclusions>
         </dependency>
-
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-simple</artifactId>
-            <version>${org.slf4j.slf4j-simple.version}</version>
+            <version>${org.slf4j.version}</version>
             <scope>test</scope>
         </dependency>
     </dependencies>
@@ -63,8 +61,7 @@
     <properties>
         <thrift.version>0.10.0</thrift.version>
         <maven-thrift.version>0.1.11</maven-thrift.version>
-        <org.slf4j.slf4j-simple.version>1.7.12</org.slf4j.slf4j-simple.version>
         <build-helper-maven-plugin.version>3.0.0</build-helper-maven-plugin.version>
     </properties>
 
-</project>
+</project>

apache-tika/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>

apache-velocity/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>

asciidoctor/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -69,4 +68,4 @@
         <asciidoctorj-pdf.plugin.version>1.5.0-alpha.15</asciidoctorj-pdf.plugin.version>
     </properties>
 
-</project>
+</project>

asm/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>

atomikos/pom.xml

@@ -1,128 +1,128 @@
 <?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"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
-	<modelVersion>4.0.0</modelVersion>
+    <modelVersion>4.0.0</modelVersion>
-	<artifactId>atomikos</artifactId>
+    <artifactId>atomikos</artifactId>
-	<name>atomikos</name>
+    <name>atomikos</name>
 
-	<parent>
+    <parent>
-		<groupId>com.baeldung</groupId>
+        <groupId>com.baeldung</groupId>
-		<artifactId>parent-modules</artifactId>
+        <artifactId>parent-modules</artifactId>
-		<version>1.0.0-SNAPSHOT</version>
+        <version>1.0.0-SNAPSHOT</version>
-	</parent>
+    </parent>
 
-	<dependencies>
+    <dependencies>
-		<dependency>
+        <dependency>
-			<groupId>com.atomikos</groupId>
+            <groupId>com.atomikos</groupId>
-			<artifactId>transactions-jdbc</artifactId>
+            <artifactId>transactions-jdbc</artifactId>
-			<version>${atomikos-version}</version>
+            <version>${atomikos-version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>com.atomikos</groupId>
+            <groupId>com.atomikos</groupId>
-			<artifactId>transactions-jms</artifactId>
+            <artifactId>transactions-jms</artifactId>
-			<version>${atomikos-version}</version>
+            <version>${atomikos-version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>com.atomikos</groupId>
+            <groupId>com.atomikos</groupId>
-			<artifactId>transactions-hibernate4</artifactId>
+            <artifactId>transactions-hibernate4</artifactId>
-			<version>${atomikos-version}</version>
+            <version>${atomikos-version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>org.springframework</groupId>
+            <groupId>org.springframework</groupId>
-			<artifactId>spring-context</artifactId>
+            <artifactId>spring-context</artifactId>
-			<version>${spring-version}</version>
+            <version>${spring-version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>org.springframework</groupId>
+            <groupId>org.springframework</groupId>
-			<artifactId>spring-tx</artifactId>
+            <artifactId>spring-tx</artifactId>
-			<version>${spring-version}</version>
+            <version>${spring-version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>org.springframework.data</groupId>
+            <groupId>org.springframework.data</groupId>
-			<artifactId>spring-data-jpa</artifactId>
+            <artifactId>spring-data-jpa</artifactId>
-			<version>${spring-data-jpa.version}</version>
+            <version>${spring-data-jpa.version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>org.springframework</groupId>
+            <groupId>org.springframework</groupId>
-			<artifactId>spring-test</artifactId>
+            <artifactId>spring-test</artifactId>
-			<version>${spring-version}</version>
+            <version>${spring-version}</version>
-			<scope>test</scope>
+            <scope>test</scope>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>org.hibernate</groupId>
+            <groupId>org.hibernate</groupId>
-			<artifactId>hibernate-core</artifactId>
+            <artifactId>hibernate-core</artifactId>
-			<version>${hibernate.version}</version>
+            <version>${hibernate.version}</version>
-			<scope>provided</scope>
+            <scope>provided</scope>
-			<exclusions>
+            <exclusions>
-				<exclusion>
+                <exclusion>
-					<groupId>javax.transaction</groupId>
+                    <groupId>javax.transaction</groupId>
-					<artifactId>jta</artifactId>
+                    <artifactId>jta</artifactId>
-				</exclusion>
+                </exclusion>
-			</exclusions>
+            </exclusions>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>org.apache.activemq</groupId>
+            <groupId>org.apache.activemq</groupId>
-			<artifactId>activemq-core</artifactId>
+            <artifactId>activemq-core</artifactId>
-			<version>${activemq-core.version}</version>
+            <version>${activemq-core.version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>org.apache.derby</groupId>
+            <groupId>org.apache.derby</groupId>
-			<artifactId>derby</artifactId>
+            <artifactId>derby</artifactId>
-			<version>${derby.version}</version>
+            <version>${derby.version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>junit</groupId>
+            <groupId>org.junit.vintage</groupId>
-			<artifactId>junit</artifactId>
+            <artifactId>junit-vintage-engine</artifactId>
-			<version>${junit.version}</version>
+            <version>${junit-jupiter.version}</version>
-			<scope>test</scope>
+            <scope>test</scope>
-		</dependency>
+        </dependency>
-		<!-- the JTA API -->
+        <!-- the JTA API -->
-		<dependency>
+        <dependency>
-			<groupId>javax.transaction</groupId>
+            <groupId>javax.transaction</groupId>
-			<artifactId>jta</artifactId>
+            <artifactId>jta</artifactId>
-			<version>${jta.version}</version>
+            <version>${jta.version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>org.apache.geronimo.specs</groupId>
+            <groupId>org.apache.geronimo.specs</groupId>
-			<artifactId>geronimo-jta_1.0.1B_spec</artifactId>
+            <artifactId>geronimo-jta_1.0.1B_spec</artifactId>
-			<version>${geronimo.version}</version>
+            <version>${geronimo.version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>javax.validation</groupId>
+            <groupId>javax.validation</groupId>
-			<artifactId>validation-api</artifactId>
+            <artifactId>validation-api</artifactId>
-			<version>${validation-api.version}</version>
+            <version>${validation-api.version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>org.hibernate.validator</groupId>
+            <groupId>org.hibernate.validator</groupId>
-			<artifactId>hibernate-validator</artifactId>
+            <artifactId>hibernate-validator</artifactId>
-			<version>${hibernate-validator.version}</version>
+            <version>${hibernate-validator.version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>javax.el</groupId>
+            <groupId>javax.el</groupId>
-			<artifactId>javax.el-api</artifactId>
+            <artifactId>javax.el-api</artifactId>
-			<version>${javax.el-api.version}</version>
+            <version>${javax.el-api.version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-			<groupId>org.glassfish.web</groupId>
+            <groupId>org.glassfish.web</groupId>
-			<artifactId>javax.el</artifactId>
+            <artifactId>javax.el</artifactId>
-			<version>${javax.el.version}</version>
+            <version>${javax.el.version}</version>
-		</dependency>
+        </dependency>
-	</dependencies>
+    </dependencies>
 
-	<properties>
+    <properties>
-		<atomikos-version>5.0.6</atomikos-version>
+        <atomikos-version>5.0.6</atomikos-version>
-		<spring-version>5.1.6.RELEASE</spring-version>
+        <spring-version>5.1.6.RELEASE</spring-version>
-		<hibernate.version>5.4.3.Final</hibernate.version>
+        <hibernate.version>5.4.3.Final</hibernate.version>
-		<spring-data-jpa.version>1.11.23.RELEASE</spring-data-jpa.version>
+        <spring-data-jpa.version>1.11.23.RELEASE</spring-data-jpa.version>
-		<activemq-core.version>5.7.0</activemq-core.version>
+        <activemq-core.version>5.7.0</activemq-core.version>
-		<derby.version>10.8.1.2</derby.version>
+        <derby.version>10.8.1.2</derby.version>
-		<jta.version>1.1</jta.version>
+        <jta.version>1.1</jta.version>
-		<geronimo.version>1.0</geronimo.version>
+        <geronimo.version>1.0</geronimo.version>
-		<validation-api.version>2.0.1.Final</validation-api.version>
+        <validation-api.version>2.0.1.Final</validation-api.version>
-		<hibernate-validator.version>6.1.2.Final</hibernate-validator.version>
+        <hibernate-validator.version>6.1.2.Final</hibernate-validator.version>
-		<javax.el-api.version>3.0.0</javax.el-api.version>
+        <javax.el-api.version>3.0.0</javax.el-api.version>
-		<javax.el.version>2.2.4</javax.el.version>
+        <javax.el.version>2.2.4</javax.el.version>
-	</properties>
+    </properties>
 
 </project>

atomix/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-    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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
@@ -32,4 +31,4 @@
         <atomix-all.version>1.0.0-rc9</atomix-all.version>
     </properties>
 
-</project>
+</project>

aws-app-sync/pom.xml

@@ -1,11 +1,12 @@
 <?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"
+<project xmlns="http://maven.apache.org/POM/4.0.0"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    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>
     <artifactId>aws-app-sync</artifactId>
     <name>aws-app-sync</name>
     <description>Spring Boot using AWS App Sync</description>
-    
+
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>parent-boot-2</artifactId>
@@ -14,12 +15,10 @@
     </parent>
 
     <dependencies>
-
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
         </dependency>
-
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>
@@ -46,4 +45,4 @@
         </plugins>
     </build>
 
-</project>
+</project>