[1.8.x] + fix issue AsyncHttpClient#637

AsyncHttpClient#637
"AHC with Grizzly provider not handling SSL Connect/tunnelling with Proxy"

Author: oleksiys

src/main/java/com/ning/http/client/providers/grizzly/GrizzlyAsyncHttpProvider.java

@@ -1477,7 +1477,22 @@ protected void onHttpHeadersParsed(HttpHeader httpHeader,
 
         }
 
-
+        @Override
+        protected boolean onHttpHeaderParsed(final HttpHeader httpHeader,
+                final Buffer buffer, final FilterChainContext ctx) {
+            super.onHttpHeaderParsed(httpHeader, buffer, ctx);
+            
+            final HttpRequestPacket request = ((HttpResponsePacket) httpHeader).getRequest();
+            if (Method.CONNECT.equals(request.getMethod())) {
+                // finish request/response processing, because Grizzly itself
+                // treats CONNECT traffic as part of request-response processing
+                // and we don't want it be treated like that
+                httpHeader.setExpectContent(false);
+            }
+            
+            return false;
+        }
+        
         @SuppressWarnings({"unchecked"})
         @Override
         protected boolean onHttpPacketParsed(HttpHeader httpHeader, FilterChainContext ctx) {