Minor performance optimization in handling of HEAD requests by the H2 transport

Author: ok2c

httpcore5-h2/src/main/java/org/apache/hc/core5/http2/impl/nio/ServerH2StreamHandler.java

@@ -179,7 +179,7 @@ private void commitResponse(
                     receivedRequest != null && Method.HEAD.isSame(receivedRequest.getMethod());
             outputChannel.submit(responseHeaders, endStream);
             connMetrics.incrementResponseCount();
-            if (responseEntityDetails == null) {
+            if (endStream) {
                 responseState = MessageState.COMPLETE;
             } else {
                 responseState = MessageState.BODY;