Correctly include the stream id when convert from Http2HeadersFrame to HttpMessage

Motivation:

We did not correctly set the stream id in the headers of HttpMessage when converting a Http2HeadersFrame. This is based on https://github.com/netty/netty/pull/7778 so thanks to @jprante.

Modifications:

- Correctly set the id when possible in the header.
- Add test case

Result:

Correctly include stream id.

codec-http2/src/main/java/io/netty/handler/codec/http2/Http2StreamFrameToHttpObjectCodec.java

@@ -81,9 +81,10 @@ public class Http2StreamFrameToHttpObjectCodec extends MessageToMessageCodec<Htt
     @Override
     protected void decode(ChannelHandlerContext ctx, Http2StreamFrame frame, List<Object> out) throws Exception {
         if (frame instanceof Http2HeadersFrame) {
-            int id = 0; // not really the id
             Http2HeadersFrame headersFrame = (Http2HeadersFrame) frame;
             Http2Headers headers = headersFrame.headers();
+            Http2FrameStream stream = headersFrame.stream();
+            int id = stream == null ? 0 : stream.id();
 
             final CharSequence status = headers.status();
 

codec-http2/src/test/java/io/netty/handler/codec/http2/Http2StreamFrameToHttpObjectCodecTest.java

@@ -745,12 +745,36 @@ public class Http2StreamFrameToHttpObjectCodecTest {
 
     @Test
     public void testDecodeFullResponseHeaders() throws Exception {
+        testDecodeFullResponseHeaders(false);
+    }
+
+    @Test
+    public void testDecodeFullResponseHeadersWithStreamID() throws Exception {
+        testDecodeFullResponseHeaders(true);
+    }
+
+    private void testDecodeFullResponseHeaders(boolean withStreamId) throws Exception {
         EmbeddedChannel ch = new EmbeddedChannel(new Http2StreamFrameToHttpObjectCodec(false));
         Http2Headers headers = new DefaultHttp2Headers();
         headers.scheme(HttpScheme.HTTP.name());
         headers.status(HttpResponseStatus.OK.codeAsText());
 
-        assertTrue(ch.writeInbound(new DefaultHttp2HeadersFrame(headers, true)));
+        Http2HeadersFrame frame = new DefaultHttp2HeadersFrame(headers, true);
+        if (withStreamId) {
+            frame.stream(new Http2FrameStream() {
+                @Override
+                public int id() {
+                    return 1;
+                }
+
+                @Override
+                public Http2Stream.State state() {
+                    return Http2Stream.State.OPEN;
+                }
+            });
+        }
+
+        assertTrue(ch.writeInbound(frame));
 
         FullHttpResponse response = ch.readInbound();
         try {
@@ -759,6 +783,10 @@ public class Http2StreamFrameToHttpObjectCodecTest {
             assertThat(response.content().readableBytes(), is(0));
             assertTrue(response.trailingHeaders().isEmpty());
             assertFalse(HttpUtil.isTransferEncodingChunked(response));
+            if (withStreamId) {
+                assertEquals(1,
+                        (int) response.headers().getInt(HttpConversionUtil.ExtensionHeaderNames.STREAM_ID.text()));
+            }
         } finally {
             response.release();
         }