Initial support for Servlet 6.1

Closes gh-31159

Author: jhoeller

Diff for: spring-test/src/main/java/org/springframework/mock/web/MockHttpServletResponse.java

@@ -623,10 +623,15 @@ public void sendError(int status) throws IOException {
 
 	@Override
 	public void sendRedirect(String url) throws IOException {
+		sendRedirect(url, HttpServletResponse.SC_MOVED_TEMPORARILY, true);
+	}
+
+	// @Override - on Servlet 6.1
+	public void sendRedirect(String url, int sc, boolean clearBuffer) throws IOException {
 		Assert.state(!isCommitted(), "Cannot send redirect - response is already committed");
 		Assert.notNull(url, "Redirect URL must not be null");
 		setHeader(HttpHeaders.LOCATION, url);
-		setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
+		setStatus(sc);
 		setCommitted(true);
 	}
 
@@ -775,7 +780,7 @@ private void setCookie(Cookie cookie) {
 
 	@Override
 	public void setStatus(int status) {
-		if (!this.isCommitted()) {
+		if (!isCommitted()) {
 			this.status = status;
 		}
 	}

Diff for: spring-test/src/test/java/org/springframework/mock/web/MockHttpServletResponseTests.java

@@ -201,7 +201,7 @@ void setCharacterEncodingNull() {
 		response.setCharacterEncoding("UTF-8");
 		assertThat(response.getContentType()).isEqualTo("test/plain;charset=UTF-8");
 		assertThat(response.getHeader(CONTENT_TYPE)).isEqualTo("test/plain;charset=UTF-8");
-		response.setCharacterEncoding(null);
+		response.setCharacterEncoding((String) null);
 		assertThat(response.getContentType()).isEqualTo("test/plain");
 		assertThat(response.getHeader(CONTENT_TYPE)).isEqualTo("test/plain");
 		assertThat(response.getCharacterEncoding()).isEqualTo(WebUtils.DEFAULT_CHARACTER_ENCODING);

Diff for: spring-web/src/testFixtures/java/org/springframework/web/testfixture/servlet/MockHttpServletResponse.java

@@ -623,10 +623,15 @@ public void sendError(int status) throws IOException {
 
 	@Override
 	public void sendRedirect(String url) throws IOException {
+		sendRedirect(url, HttpServletResponse.SC_MOVED_TEMPORARILY, true);
+	}
+
+	// @Override - on Servlet 6.1
+	public void sendRedirect(String url, int sc, boolean clearBuffer) throws IOException {
 		Assert.state(!isCommitted(), "Cannot send redirect - response is already committed");
 		Assert.notNull(url, "Redirect URL must not be null");
 		setHeader(HttpHeaders.LOCATION, url);
-		setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
+		setStatus(sc);
 		setCommitted(true);
 	}
 
@@ -775,7 +780,7 @@ private void setCookie(Cookie cookie) {
 
 	@Override
 	public void setStatus(int status) {
-		if (!this.isCommitted()) {
+		if (!isCommitted()) {
 			this.status = status;
 		}
 	}
@@ -785,6 +790,9 @@ public int getStatus() {
 		return this.status;
 	}
 
+	/**
+	 * Return the error message used when calling {@link HttpServletResponse#sendError(int, String)}.
+	 */
 	@Nullable
 	public String getErrorMessage() {
 		return this.errorMessage;

Diff for: spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequest.java

@@ -679,6 +679,11 @@ public void sendRedirect(String location) throws IOException {
 			throw new UnsupportedOperationException();
 		}
 
+		// @Override - on Servlet 6.1
+		public void sendRedirect(String location, int sc, boolean clearBuffer) throws IOException {
+			throw new UnsupportedOperationException();
+		}
+
 		@Override
 		public void addDateHeader(String name, long date) {
 			throw new UnsupportedOperationException();