Merge branch '6.2.x'

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

@@ -59,9 +59,10 @@ import org.springframework.util.ObjectUtils;
 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<>();
+	public static final HttpEntity<?> EMPTY = new HttpEntity<>(HttpHeaders.EMPTY);
 
 
 	private final HttpHeaders headers;

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

@@ -23,7 +23,10 @@ import org.junit.jupiter.api.Test;
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
+ * Unit tests for {@link HttpEntity}.
+ *
  * @author Arjen Poutsma
+ * @author Yanming Zhou
  */
 class HttpEntityTests {
 
@@ -31,6 +34,7 @@ class HttpEntityTests {
 	void noHeaders() {
 		String body = "foo";
 		HttpEntity<String> entity = new HttpEntity<>(body);
+
 		assertThat(entity.getBody()).isSameAs(body);
 		assertThat(entity.getHeaders().isEmpty()).as("isEmpty").isTrue();
 	}
@@ -41,6 +45,7 @@ class HttpEntityTests {
 		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");
@@ -52,6 +57,7 @@ class HttpEntityTests {
 		headers.set("Content-Type", "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");
@@ -120,4 +126,14 @@ class HttpEntityTests {
 		assertThat(requestEntity2).isEqualTo(requestEntity);
 	}
 
+	@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();
+	}
+
 }