From 4178a00735fc9dec0def556f1fcd7d5bd17ad3d7 Mon Sep 17 00:00:00 2001
From: Terry Tao <yueyang.tao@gmail.com>
Date: Fri, 19 Dec 2025 17:26:39 -0500
Subject: [PATCH] Fix LinkedCaseInsensitiveMap entrySet case-insensitivity

Signed-off-by: Terry Tao <yueyang.tao@gmail.com>
---
 .../util/LinkedCaseInsensitiveMap.java        | 33 +++++++++++++++----
 .../util/LinkedCaseInsensitiveMapTests.java   | 16 +++++++++
 2 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/spring-core/src/main/java/org/springframework/util/LinkedCaseInsensitiveMap.java b/spring-core/src/main/java/org/springframework/util/LinkedCaseInsensitiveMap.java
index 02c60c1201bd..849d38b33fd0 100644
--- a/spring-core/src/main/java/org/springframework/util/LinkedCaseInsensitiveMap.java
+++ b/spring-core/src/main/java/org/springframework/util/LinkedCaseInsensitiveMap.java
@@ -448,7 +448,18 @@ public int size() {
 
 		@Override
 		public boolean contains(Object o) {
-			return this.delegate.contains(o);
+			if (!(o instanceof Map.Entry<?, ?> entry)) {
+				return false;
+			}
+			Object key = entry.getKey();
+			if (!(key instanceof String stringKey)) {
+				return false;
+			}
+			if (!LinkedCaseInsensitiveMap.this.containsKey(stringKey)) {
+				return false;
+			}
+			V value = LinkedCaseInsensitiveMap.this.get(stringKey);
+			return ObjectUtils.nullSafeEquals(value, entry.getValue());
 		}
 
 		@Override
@@ -457,13 +468,23 @@ public Iterator<Entry<String, V>> iterator() {
 		}
 
 		@Override
-		@SuppressWarnings("unchecked")
 		public boolean remove(Object o) {
-			if (this.delegate.remove(o)) {
-				removeCaseInsensitiveKey(((Map.Entry<String, V>) o).getKey());
-				return true;
+			if (!(o instanceof Map.Entry<?, ?> entry)) {
+				return false;
+			}
+			Object key = entry.getKey();
+			if (!(key instanceof String stringKey)) {
+				return false;
+			}
+			if (!LinkedCaseInsensitiveMap.this.containsKey(stringKey)) {
+				return false;
+			}
+			V value = LinkedCaseInsensitiveMap.this.get(stringKey);
+			if (!ObjectUtils.nullSafeEquals(value, entry.getValue())) {
+				return false;
 			}
-			return false;
+			LinkedCaseInsensitiveMap.this.remove(stringKey);
+			return true;
 		}
 
 		@Override
diff --git a/spring-core/src/test/java/org/springframework/util/LinkedCaseInsensitiveMapTests.java b/spring-core/src/test/java/org/springframework/util/LinkedCaseInsensitiveMapTests.java
index 21799eccf3ce..43840c6168d2 100644
--- a/spring-core/src/test/java/org/springframework/util/LinkedCaseInsensitiveMapTests.java
+++ b/spring-core/src/test/java/org/springframework/util/LinkedCaseInsensitiveMapTests.java
@@ -17,6 +17,7 @@
 package org.springframework.util;
 
 import java.util.Iterator;
+import java.util.Map;
 
 import org.junit.jupiter.api.Test;
 
@@ -218,6 +219,21 @@ void removeFromEntrySetViaIterator() {
 		assertThat(map.get("key")).isEqualTo("newvalue");
 	}
 
+	@Test
+	void entrySetContainsIsCaseInsensitive() {
+		map.put("Key", "value");
+		assertThat(map.entrySet().contains(Map.entry("KEY", "value"))).isTrue();
+		assertThat(map.entrySet().contains(Map.entry("key", "value"))).isTrue();
+		assertThat(map.entrySet().contains(Map.entry("Key", "value"))).isTrue();
+	}
+
+	@Test
+	void entrySetRemoveIsCaseInsensitive() {
+		map.put("Key", "value");
+		assertThat(map.entrySet().remove(Map.entry("KEY", "value"))).isTrue();
+		assertThat(map).isEmpty();
+	}
+
 	private void nextAndRemove(Iterator<?> iterator) {
 		iterator.next();
 		iterator.remove();