LinkedCaseInsensitiveMap checks for uniqueness of case-insensitive keys now

Issue: SPR-9754

spring-core/src/main/java/org/springframework/util/LinkedCaseInsensitiveMap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -88,7 +88,10 @@ public class LinkedCaseInsensitiveMap<V> extends LinkedHashMap<String, V> {
 
 	@Override
 	public V put(String key, V value) {
-		this.caseInsensitiveKeys.put(convertKey(key), key);
+		String oldKey = this.caseInsensitiveKeys.put(convertKey(key), key);
+		if (oldKey != null && !oldKey.equals(key)) {
+			super.remove(oldKey);
+		}
 		return super.put(key, value);
 	}
 

spring-core/src/test/java/org/springframework/util/LinkedCaseInsensitiveMapTests.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2002-2012 the original author or authors.
+ *
+ * Licensed 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.
+ */
+
+package org.springframework.util;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ * @author Juergen Hoeller
+ */
+public class LinkedCaseInsensitiveMapTests {
+
+	private LinkedCaseInsensitiveMap<String> map;
+
+	@Before
+	public void setUp() {
+		map = new LinkedCaseInsensitiveMap<String>();
+	}
+
+	@Test
+	public void putAndGet() {
+		map.put("key", "value1");
+		map.put("key", "value2");
+		map.put("key", "value3");
+		assertEquals(1, map.size());
+		assertEquals("value3", map.get("key"));
+		assertEquals("value3", map.get("KEY"));
+		assertEquals("value3", map.get("Key"));
+	}
+
+	@Test
+	public void putWithOverlappingKeys() {
+		map.put("key", "value1");
+		map.put("KEY", "value2");
+		map.put("Key", "value3");
+		assertEquals(1, map.size());
+		assertEquals("value3", map.get("key"));
+		assertEquals("value3", map.get("KEY"));
+		assertEquals("value3", map.get("Key"));
+	}
+
+}