Fix #981. Add status codes from RFC 6585.

Author: markt-asf

api/src/main/java/jakarta/servlet/http/HttpServletResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2025 Oracle and/or its affiliates and others.
+ * Copyright (c) 1997, 2026 Oracle and/or its affiliates and others.
  * All rights reserved.
  * Copyright 2004 The Apache Software Foundation
  *
@@ -745,6 +745,22 @@ default Supplier<Map<String, String>> getTrailerFields() {
      */
     int SC_UPGRADE_REQUIRED = 426;
 
+    /**
+     * Status code (428) indicating that the origin server requires this request to be conditional.
+     */
+    int SC_PRECONDITION_REQUIRED = 428;
+
+    /**
+     * Status code (429) indicating that the user has sent too many requests in a given amount of time ("rate limiting").
+     */
+    int SC_TOO_MANY_REQUESTS = 429;
+
+    /**
+     * Status code (431) indicating that the server is unwilling to process the request because its header fields are too
+     * large.
+     */
+    int SC_REQUEST_HEADER_FIELS_TOO_LARGE = 431;
+
     /**
      * Status code (500) indicating an error inside the HTTP server which prevented it from fulfilling the request.
      */
@@ -777,4 +793,9 @@ default Supplier<Map<String, String>> getTrailerFields() {
      * was used in the request message.
      */
     int SC_HTTP_VERSION_NOT_SUPPORTED = 505;
+
+    /**
+     * Status code (511) indicating that the client needs to authenticate to gain network access.
+     */
+    int SC_NETWORK_AUTHENTICATION_REQUIRED = 511;
 }

spec/src/main/asciidoc/servlet-spec-body.adoc

@@ -120,6 +120,8 @@ Generic Syntax
 
 * RFC 6265 HTTP State Management Mechanism
 
+* RFC 6585 Additional HTTP Status Codes
+
 * RFC 7258 Pervasive Monitoring Is an Attack
 
 * RFC 7541 HPACK: Header Compression for HTTP/2 (HPACK)
@@ -8588,6 +8590,9 @@ link:https://github.com/jakartaee/servlet/issues/867[Issue 867]::
 When processing the `If-Modified-Since` header in `HttpServerlet.service()`,
 invalid header values must be ignored as per RFC 9110.
 
+link:https://github.com/jakartaee/servlet/issues/981[Issue 981]::
+Add constants to `HttpServletResponse` for the status codes defined in RFC 6585.
+
 link:https://github.com/jakartaee/servlet/issues/994[Issue 994]::
 The value returned by `HttpServletRequest.getpathInfo()` does not contain path paremeter information.