371903: Implement servlet 3.0 spec change (spec section 9.4) to not commit response in Dispatcher.forward() when request.isAysncStarted()

Signed-off-by: Greg Wilkins <gregw@webtide.com>

jetty-server/src/main/java/org/eclipse/jetty/server/Dispatcher.java

@@ -287,21 +287,9 @@ public class Dispatcher implements RequestDispatcher
                 
                 _contextHandler.handle(_path,baseRequest, (HttpServletRequest)request, (HttpServletResponse)response);
                 
-                if (baseRequest.getResponse().isWriting())
+                if (!request.isAsyncStarted())
                 {
-                    try {response.getWriter().close();}
+                    commitResponse(response,baseRequest);
-                    catch(IllegalStateException e) 
-                    { 
-                        response.getOutputStream().close(); 
-                    }
-                }
-                else
-                {
-                    try {response.getOutputStream().close();}
-                    catch(IllegalStateException e) 
-                    { 
-                        response.getWriter().close(); 
-                    }
                 }
             }
         }
@@ -320,6 +308,33 @@ public class Dispatcher implements RequestDispatcher
     }
 
 
+    private void commitResponse(ServletResponse response, Request baseRequest) throws IOException
+    {
+        if (baseRequest.getResponse().isWriting())
+        {
+            try
+            {
+                response.getWriter().close();
+            }
+            catch (IllegalStateException e)
+            {
+                response.getOutputStream().close();
+            }
+        }
+        else
+        {
+            try
+            {
+                response.getOutputStream().close();
+            }
+            catch (IllegalStateException e)
+            {
+                response.getWriter().close();
+            }
+        }
+    }
+
+
     /* ------------------------------------------------------------ */
     /* ------------------------------------------------------------ */
     /* ------------------------------------------------------------ */