LinkedCaseInsensitiveMap provides reliable getOrDefault implementation

Issue: SPR-13981
(cherry picked from commit 7a32ce3)

Author: jhoeller

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -114,21 +114,35 @@ public boolean containsKey(Object key) {
 	@Override
 	public V get(Object key) {
 		if (key instanceof String) {
-			return super.get(this.caseInsensitiveKeys.get(convertKey((String) key)));
+			String caseInsensitiveKey = this.caseInsensitiveKeys.get(convertKey((String) key));
+			if (caseInsensitiveKey != null) {
+				return super.get(caseInsensitiveKey);
+			}
 		}
-		else {
-			return null;
+		return null;
+	}
+
+	// Overridden to avoid LinkedHashMap's own hash computation in its getOrDefault impl
+	@Override
+	public V getOrDefault(Object key, V defaultValue) {
+		if (key instanceof String) {
+			String caseInsensitiveKey = this.caseInsensitiveKeys.get(convertKey((String) key));
+			if (caseInsensitiveKey != null) {
+				return super.get(caseInsensitiveKey);
+			}
 		}
+		return defaultValue;
 	}
 
 	@Override
 	public V remove(Object key) {
-		if (key instanceof String ) {
-			return super.remove(this.caseInsensitiveKeys.remove(convertKey((String) key)));
-		}
-		else {
-			return null;
+		if (key instanceof String) {
+			String caseInsensitiveKey = this.caseInsensitiveKeys.remove(convertKey((String) key));
+			if (caseInsensitiveKey != null) {
+				return super.remove(caseInsensitiveKey);
+			}
 		}
+		return null;
 	}
 
 	@Override

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -16,7 +16,6 @@
 
 package org.springframework.util;
 
-import org.junit.Before;
 import org.junit.Test;
 
 import static org.junit.Assert.*;
@@ -26,12 +25,8 @@
  */
 public class LinkedCaseInsensitiveMapTests {
 
-	private LinkedCaseInsensitiveMap<String> map;
+	private final LinkedCaseInsensitiveMap<String> map = new LinkedCaseInsensitiveMap<String>();
 
-	@Before
-	public void setUp() {
-		map = new LinkedCaseInsensitiveMap<String>();
-	}
 
 	@Test
 	public void putAndGet() {
@@ -55,4 +50,28 @@ public void putWithOverlappingKeys() {
 		assertEquals("value3", map.get("Key"));
 	}
 
+	@Test
+	public void getOrDefault() {
+		map.put("key", "value1");
+		map.put("KEY", "value2");
+		map.put("Key", "value3");
+		assertEquals("value3", map.getOrDefault("key", "N"));
+		assertEquals("value3", map.getOrDefault("KEY", "N"));
+		assertEquals("value3", map.getOrDefault("Key", "N"));
+		assertEquals("N", map.getOrDefault("keeeey", "N"));
+		assertEquals("N", map.getOrDefault(new Object(), "N"));
+	}
+
+	@Test
+	public void getOrDefaultWithNullValue() {
+		map.put("key", null);
+		map.put("KEY", null);
+		map.put("Key", null);
+		assertNull(map.getOrDefault("key", "N"));
+		assertNull(map.getOrDefault("KEY", "N"));
+		assertNull(map.getOrDefault("Key", "N"));
+		assertEquals("N", map.getOrDefault("keeeey", "N"));
+		assertEquals("N", map.getOrDefault(new Object(), "N"));
+	}
+
 }