Polishing contribution

Closes gh-34812

Author: rstoyanchev

spring-web/src/main/java/org/springframework/http/HttpEntity.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -49,7 +49,6 @@
  *
  * @author Arjen Poutsma
  * @author Juergen Hoeller
- * @author Yanming Zhou
  * @since 3.0.2
  * @param <T> the body type
  * @see org.springframework.web.client.RestTemplate
@@ -59,7 +58,8 @@
 public class HttpEntity<T> {
 
 	/**
-	 * The empty {@code HttpEntity}, with no body or headers.
+	 * An {@code HttpEntity} instance with a {@code null} body and
+	 * {@link HttpHeaders#EMPTY empty headers}.
 	 */
 	public static final HttpEntity<?> EMPTY = new HttpEntity<>(HttpHeaders.EMPTY);
 

spring-web/src/test/java/org/springframework/http/HttpEntityTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -26,6 +26,8 @@
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
+ * Unit tests for {@link HttpEntity}.
+ *
  * @author Arjen Poutsma
  * @author Yanming Zhou
  */
@@ -35,6 +37,7 @@ class HttpEntityTests {
 	void noHeaders() {
 		String body = "foo";
 		HttpEntity<String> entity = new HttpEntity<>(body);
+
 		assertThat(entity.getBody()).isSameAs(body);
 		assertThat(entity.getHeaders()).isEmpty();
 	}
@@ -45,6 +48,7 @@ void httpHeaders() {
 		headers.setContentType(MediaType.TEXT_PLAIN);
 		String body = "foo";
 		HttpEntity<String> entity = new HttpEntity<>(body, headers);
+
 		assertThat(entity.getBody()).isEqualTo(body);
 		assertThat(entity.getHeaders().getContentType()).isEqualTo(MediaType.TEXT_PLAIN);
 		assertThat(entity.getHeaders().getFirst("Content-Type")).isEqualTo("text/plain");
@@ -56,6 +60,7 @@ void multiValueMap() {
 		map.set("Content-Type", "text/plain");
 		String body = "foo";
 		HttpEntity<String> entity = new HttpEntity<>(body, map);
+
 		assertThat(entity.getBody()).isEqualTo(body);
 		assertThat(entity.getHeaders().getContentType()).isEqualTo(MediaType.TEXT_PLAIN);
 		assertThat(entity.getHeaders().getFirst("Content-Type")).isEqualTo("text/plain");
@@ -124,11 +129,14 @@ void requestEntity() {
 		assertThat(requestEntity2).isEqualTo(requestEntity);
 	}
 
-	@Test
-	void emptyHttpEntityShouldBeImmutable() {
-		HttpHeaders newHeaders = new HttpHeaders(HttpEntity.EMPTY.getHeaders());
-		newHeaders.add("Authorization", "Bearer some-token");
-		assertThat(HttpEntity.EMPTY.getHeaders().headerNames()).isEmpty();
+	@Test // gh-34806
+	void mutateEmptyInstanceHeaders() {
+		HttpHeaders headers = new HttpHeaders(HttpEntity.EMPTY.getHeaders());
+		headers.add("Authorization", "Bearer some-token");
+
+		assertThat(HttpEntity.EMPTY.getHeaders())
+				.as("Headers of HttpEntity.EMPTY should remain empty")
+				.isEmpty();
 	}
 
 }