Fix reference count issue when using Http2FrameCodec / Http2MultiplexCodec with HttpServerUpgradeHandler

Motivation:

When using  Http2FrameCodec / Http2MultiplexCodec with HttpServerUpgradeHandler reference count exception will be triggered.

Modifications:

- Correctly retain before calling InboundHttpToHttp2Adapter.handle
- Add unit test

Result:

Fixes [#7172].

codec-http2/src/main/java/io/netty/handler/codec/http2/Http2FrameCodec.java

@@ -248,7 +248,7 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
                 upgrade.upgradeRequest().headers().setInt(
                         HttpConversionUtil.ExtensionHeaderNames.STREAM_ID.text(), HTTP_UPGRADE_STREAM_ID);
                 InboundHttpToHttp2Adapter.handle(
-                        ctx, connection(), decoder().frameListener(), upgrade.upgradeRequest());
+                        ctx, connection(), decoder().frameListener(), upgrade.upgradeRequest().retain());
             } finally {
                 upgrade.release();
             }

codec-http2/src/test/java/io/netty/handler/codec/http2/Http2FrameCodecTest.java

@@ -24,9 +24,13 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelPromise;
 import io.netty.channel.embedded.EmbeddedChannel;
 import io.netty.handler.codec.UnsupportedMessageTypeException;
+import io.netty.handler.codec.http.DefaultFullHttpRequest;
+import io.netty.handler.codec.http.FullHttpRequest;
 import io.netty.handler.codec.http.HttpMethod;
 import io.netty.handler.codec.http.HttpResponseStatus;
 import io.netty.handler.codec.http.HttpScheme;
+import io.netty.handler.codec.http.HttpServerUpgradeHandler;
+import io.netty.handler.codec.http.HttpVersion;
 import io.netty.handler.codec.http2.Http2Exception.StreamException;
 import io.netty.handler.codec.http2.Http2Stream.State;
 import io.netty.handler.logging.LogLevel;
@@ -40,6 +44,8 @@ import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.ArgumentCaptor;
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
 
 import java.net.InetSocketAddress;
 import java.util.HashSet;
@@ -641,6 +647,31 @@ public class Http2FrameCodecTest {
         assertTrue(listenerExecuted.get());
     }
 
+    @Test
+    public void upgradeEventNoRefCntError() throws Http2Exception {
+        frameListener.onHeadersRead(http2HandlerCtx, Http2CodecUtil.HTTP_UPGRADE_STREAM_ID, request, 31, false);
+
+        final FullHttpRequest request = new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET, "/");
+        final HttpServerUpgradeHandler.UpgradeEvent upgradeEvent = mock(HttpServerUpgradeHandler.UpgradeEvent.class);
+        when(upgradeEvent.retain()).thenAnswer(new Answer<HttpServerUpgradeHandler.UpgradeEvent>() {
+            @Override
+            public HttpServerUpgradeHandler.UpgradeEvent answer(InvocationOnMock invocationOnMock) throws Throwable {
+                request.retain();
+                return upgradeEvent;
+            }
+        });
+        when(upgradeEvent.release()).thenAnswer(new Answer<Boolean>() {
+            @Override
+            public Boolean answer(InvocationOnMock invocationOnMock) throws Throwable {
+                return request.release();
+            }
+        });
+
+        when(upgradeEvent.upgradeRequest()).thenReturn(request);
+        channel.pipeline().fireUserEventTriggered(upgradeEvent);
+        assertEquals(1, request.refCnt());
+    }
+
     private static ChannelPromise anyChannelPromise() {
         return any(ChannelPromise.class);
     }

codec-http2/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker

@@ -0,0 +1 @@
+mock-maker-inline