new module has been added

java-collections-maps-3/src/test/java/com/baeldung/map/caseinsensitivekeys/CaseInsensitiveMapUnitTest.java

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+package com.baeldung.map.caseinsensitivekeys;
+
+import org.apache.commons.collections4.map.CaseInsensitiveMap;
+import org.junit.Assert;
+import org.junit.Test;
+import org.springframework.util.LinkedCaseInsensitiveMap;
+import static org.junit.Assert.*;
+
+import java.util.TreeMap;
+
+public class CaseInsensitiveMapUnitTest {
+    @Test
+    public void givenCaseInsensitiveTreeMap_whenTwoEntriesAdded_thenSizeIsOne(){
+        TreeMap<String, Integer> treeMap = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
+        treeMap.put("abc", 1);
+        treeMap.put("ABC", 2);
+
+        assertEquals(treeMap.size(), 1);
+    }
+
+    @Test
+    public void givenCommonsCaseInsensitiveMap_whenSameEntryAdded_thenValueUpdated(){
+        CaseInsensitiveMap<String, Integer> commonsHashMap = new CaseInsensitiveMap<>();
+        commonsHashMap.put("abc", 1);
+        commonsHashMap.put("ABC", 2);
+
+        Assert.assertEquals(commonsHashMap.get("aBc"), (Integer)2);
+    }
+
+    @Test
+    public void givenLinkedCaseInsensitiveMap_whenEntryRemoved_thenSizeIsZero(){
+        LinkedCaseInsensitiveMap<Integer> linkedHashMap = new LinkedCaseInsensitiveMap<>();
+        linkedHashMap.put("abc", 3);
+        linkedHashMap.remove("aBC");
+
+        Assert.assertEquals(linkedHashMap.size(), 0);
+    }
+}