Java 5065 (#11126)

* Commit source code to branch

* BAEL-5065 improvement of groupBy with complex key

core-java-modules/core-java-16/src/main/java/com/baeldung/java_16_features/groupingby/BlogPost.java

@@ -0,0 +1,38 @@
+package com.baeldung.java_16_features.groupingby;
+
+public class BlogPost {
+    
+    private String title;
+    private String author;
+    private BlogPostType type;
+    private int likes;
+    record AuthPostTypesLikes(String author, BlogPostType type, int likes) {};
+
+    public BlogPost(String title, String author, BlogPostType type, int likes) {
+        this.title = title;
+        this.author = author;
+        this.type = type;
+        this.likes = likes;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    public BlogPostType getType() {
+        return type;
+    }
+
+    public int getLikes() {
+        return likes;
+    }
+
+    @Override
+    public String toString() {
+        return "BlogPost{" + "title='" + title + '\'' + ", type=" + type + ", likes=" + likes + '}';
+    }
+}

core-java-modules/core-java-16/src/main/java/com/baeldung/java_16_features/groupingby/BlogPostType.java

@@ -0,0 +1,5 @@
+package com.baeldung.java_16_features.groupingby;
+
+public enum BlogPostType {
+    NEWS, REVIEW, GUIDE
+}

core-java-modules/core-java-16/src/main/java/com/baeldung/java_16_features/groupingby/Tuple.java

@@ -0,0 +1,41 @@
+package com.baeldung.java_16_features.groupingby;
+
+import java.util.Objects;
+
+public class Tuple {
+    private final BlogPostType type;
+    private final String author;
+
+    public Tuple(BlogPostType type, String author) {
+        this.type = type;
+        this.author = author;
+    }
+
+    public BlogPostType getType() {
+        return type;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Tuple tuple = (Tuple) o;
+        return type == tuple.type && author.equals(tuple.author);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(type, author);
+    }
+
+    @Override
+    public String toString() {
+        return "Tuple{" + "type=" + type + ", author='" + author + '\'' + '}';
+    }
+}