Fix issue with getHeaders in NoHandlerFoundException

Closes gh-29626

spring-webmvc/src/main/java/org/springframework/web/servlet/NoHandlerFoundException.java

@@ -44,7 +44,7 @@ public class NoHandlerFoundException extends ServletException implements ErrorRe
 
 	private final String requestURL;
 
-	private final HttpHeaders headers;
+	private final HttpHeaders requestHeaders;
 
 	private final ProblemDetail body;
 
@@ -59,7 +59,7 @@ public NoHandlerFoundException(String httpMethod, String requestURL, HttpHeaders
 		super("No endpoint " + httpMethod + " " + requestURL + ".");
 		this.httpMethod = httpMethod;
 		this.requestURL = requestURL;
-		this.headers = headers;
+		this.requestHeaders = headers;
 		this.body = ProblemDetail.forStatusAndDetail(getStatusCode(), getMessage());
 	}
 
@@ -76,8 +76,23 @@ public String getRequestURL() {
 		return this.requestURL;
 	}
 
+	/**
+	 * Return headers to use for the response.
+	 * <p><strong>Note:</strong> As of 6.0 this method overlaps with
+	 * {@link ErrorResponse#getHeaders()} and therefore no longer returns request
+	 * headers. Use {@link #getRequestHeaders()} instead for request headers.
+	 */
+	@Override
 	public HttpHeaders getHeaders() {
-		return this.headers;
+		return ErrorResponse.super.getHeaders();
+	}
+
+	/**
+	 * Return the headers of the request.
+	 * @since 6.0.3
+	 */
+	public HttpHeaders getRequestHeaders() {
+		return this.requestHeaders;
 	}
 
 	@Override

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ResponseEntityExceptionHandlerTests.java

@@ -253,7 +253,13 @@ public void bindException() {
 
 	@Test
 	public void noHandlerFoundException() {
-		testException(new NoHandlerFoundException("GET", "/resource", HttpHeaders.EMPTY));
+		HttpHeaders requestHeaders = new HttpHeaders();
+		requestHeaders.setContentType(MediaType.APPLICATION_FORM_URLENCODED); // gh-29626
+
+		ResponseEntity<Object> responseEntity =
+				testException(new NoHandlerFoundException("GET", "/resource", requestHeaders));
+
+		assertThat(responseEntity.getHeaders()).isEmpty();
 	}
 
 	@Test