GRAILS-10448 - replace WebUtils.exposeForwardRequestAttributes which …

…was removed from Spring 4

grails-web/src/main/groovy/org/codehaus/groovy/grails/web/util/WebUtils.java

@@ -304,7 +304,7 @@ public static String forwardRequestForUrlMappingInfo(HttpServletRequest request,
     @SuppressWarnings({ "unchecked", "rawtypes" })
     public static String forwardRequestForUrlMappingInfo(HttpServletRequest request,
             HttpServletResponse response, UrlMappingInfo info, Map model, boolean includeParams) throws ServletException, IOException {
-//        exposeForwardRequestAttributes(request);
+        exposeForwardRequestAttributes(request);
         exposeRequestAttributes(request, model);
 
         String forwardUrl = buildDispatchUrlForMapping(info, includeParams);
@@ -323,6 +323,27 @@ public static String forwardRequestForUrlMappingInfo(HttpServletRequest request,
         dispatcher.forward(request, response);
         return forwardUrl;
     }
+
+    /**
+     * Expose the current request URI and paths as {@link javax.servlet.http.HttpServletRequest}
+     * attributes under the keys defined in the Servlet 2.4 specification,
+     * for containers that implement 2.3 or an earlier version of the Servlet API:
+     * {@code javax.servlet.forward.request_uri},
+     * {@code javax.servlet.forward.context_path},
+     * {@code javax.servlet.forward.servlet_path},
+     * {@code javax.servlet.forward.path_info},
+     * {@code javax.servlet.forward.query_string}.
+     * <p>Does not override values if already present, to not cause conflicts
+     * with the attributes exposed by Servlet 2.4+ containers themselves.
+     * @param request current servlet request
+     */
+    public static void exposeForwardRequestAttributes(HttpServletRequest request) {
+        exposeRequestAttributeIfNotPresent(request, FORWARD_REQUEST_URI_ATTRIBUTE, request.getRequestURI());
+        exposeRequestAttributeIfNotPresent(request, FORWARD_CONTEXT_PATH_ATTRIBUTE, request.getContextPath());
+        exposeRequestAttributeIfNotPresent(request, FORWARD_SERVLET_PATH_ATTRIBUTE, request.getServletPath());
+        exposeRequestAttributeIfNotPresent(request, FORWARD_PATH_INFO_ATTRIBUTE, request.getPathInfo());
+        exposeRequestAttributeIfNotPresent(request, FORWARD_QUERY_STRING_ATTRIBUTE, request.getQueryString());
+    }
 
     /**
      * Include whatever the given UrlMappingInfo maps to within the current response