Java 16961 (#13236)

* [JAVA-16961] Moved code for article "Create an Empty Map in Java"

* [JAVA-16961] Alter README.md

* [JAVA-16961] Moved code for article "Sorting a Hashset in Java"

* [JAVA-16961] Added links to README.md files

* [JAVA-16961] Revert link changes

* [JAVA-16961] Replaced junit4 with junit5 annotations

* [JAVA-16961] test build

* [JAVA-16961] Added junit annotations

* [JAVA-16961] Added links

Co-authored-by: panagiotiskakos <panagiotis.kakos@libra-is.com>

core-java-modules/core-java-collections-4/README.md

@@ -7,7 +7,6 @@
 - [ArrayList vs. LinkedList vs. HashMap in Java](https://www.baeldung.com/java-arraylist-vs-linkedlist-vs-hashmap)
 - [Java Deque vs. Stack](https://www.baeldung.com/java-deque-vs-stack)
 - [Collection.toArray(new T[0]) or .toArray(new T[size])](https://www.baeldung.com/java-collection-toarray-methods)
-- [Create an Empty Map in Java](https://www.baeldung.com/java-create-empty-map)
 - [Sorting Objects in a List by Date](https://www.baeldung.com/java-sort-list-by-date)
 - [Fixed Size Queue Implementations in Java](https://www.baeldung.com/java-fixed-size-queue)
 - [Difference Between Java Enumeration and Iterator](https://www.baeldung.com/java-enumeration-vs-iterator)
@@ -15,4 +14,4 @@
 - [Guide to Java PriorityQueue](https://www.baeldung.com/java-priorityqueue)
 - [Java Generics PECS – Producer Extends Consumer Super](https://www.baeldung.com/java-generics-pecs)
 - [Reversing a Stack in Java](https://www.baeldung.com/java-reversing-a-stack)
-- [Sorting a HashSet in Java](https://www.baeldung.com/java-sort-hashset)
+- More articles: [[<-- prev]](/core-java-modules/core-java-collections-3)