Configures HTTP2 pipeline with more proper way

Motivation:

When we use pipeline.replace and we still had ongoing inbound, then
there will be some problem that inbound message would go to wrong
handlers. So we add handler first, and remove self after add, so that
the next handler will be the correct one.

Modifications:

Uses remove after addAfter instead of replace.

Result:

Fixed #6881

codec-http2/src/main/java/io/netty/handler/codec/http2/CleartextHttp2ServerUpgradeHandler.java

@@ -89,8 +89,11 @@ public final class CleartextHttp2ServerUpgradeHandler extends ChannelHandlerAdap
                 // following network traffic
                 ctx.pipeline()
                    .remove(httpServerCodec)
-                   .remove(httpServerUpgradeHandler)
+                   .remove(httpServerUpgradeHandler);
-                   .replace(this, null, http2ServerHandler);
+
+                ctx.pipeline().addAfter(ctx.name(), null, http2ServerHandler);
+                ctx.pipeline().remove(this);
+
                 ctx.fireUserEventTriggered(PriorKnowledgeUpgradeEvent.INSTANCE);
             }
         }

codec-http2/src/test/java/io/netty/handler/codec/http2/CleartextHttp2ServerUpgradeHandlerTest.java

@@ -17,8 +17,10 @@ package io.netty.handler.codec.http2;
 
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
+import io.netty.channel.Channel;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
+import io.netty.channel.ChannelInitializer;
 import io.netty.channel.embedded.EmbeddedChannel;
 import io.netty.handler.codec.http.DefaultHttpHeaders;
 import io.netty.handler.codec.http.HttpMethod;
@@ -35,7 +37,6 @@ import io.netty.handler.codec.http2.Http2Stream.State;
 import io.netty.util.CharsetUtil;
 import io.netty.util.ReferenceCountUtil;
 import org.junit.After;
-import org.junit.Before;
 import org.junit.Test;
 
 import java.util.ArrayList;
@@ -56,8 +57,7 @@ public class CleartextHttp2ServerUpgradeHandlerTest {
 
     private List<Object> userEvents;
 
-    @Before
+    private void setUpServerChannel() {
-    public void setUp() {
         frameListener = mock(Http2FrameListener.class);
 
         http2ConnectionHandler = new Http2ConnectionHandlerBuilder().frameListener(frameListener).build();
@@ -91,6 +91,8 @@ public class CleartextHttp2ServerUpgradeHandlerTest {
 
     @Test
     public void priorKnowledge() throws Exception {
+        setUpServerChannel();
+
         channel.writeInbound(Http2CodecUtil.connectionPrefaceBuf());
 
         ByteBuf settingsFrame = settingsFrameBuf();
@@ -109,6 +111,8 @@ public class CleartextHttp2ServerUpgradeHandlerTest {
 
     @Test
     public void upgrade() throws Exception {
+        setUpServerChannel();
+
         String upgradeString = "GET / HTTP/1.1\r\n" +
                                "Host: example.com\r\n" +
                                "Connection: Upgrade, HTTP2-Settings\r\n" +
@@ -138,6 +142,8 @@ public class CleartextHttp2ServerUpgradeHandlerTest {
 
     @Test
     public void priorKnowledgeInFragments() throws Exception {
+        setUpServerChannel();
+
         ByteBuf connectionPreface = Http2CodecUtil.connectionPrefaceBuf();
         assertFalse(channel.writeInbound(connectionPreface.readBytes(5), connectionPreface));
 
@@ -156,6 +162,8 @@ public class CleartextHttp2ServerUpgradeHandlerTest {
 
     @Test
     public void downgrade() throws Exception {
+        setUpServerChannel();
+
         String requestString = "GET / HTTP/1.1\r\n" +
                          "Host: example.com\r\n\r\n";
         ByteBuf inbound = Unpooled.buffer().writeBytes(requestString.getBytes(CharsetUtil.US_ASCII));
@@ -175,6 +183,45 @@ public class CleartextHttp2ServerUpgradeHandlerTest {
         assertNull(channel.readInbound());
     }
 
+    @Test
+    public void usedHttp2Codec() throws Exception {
+        final Http2Codec http2Codec = new Http2CodecBuilder(true, new ChannelInitializer<Channel>() {
+            @Override
+            protected void initChannel(Channel ch) throws Exception {
+            }
+        }).build();
+        UpgradeCodecFactory upgradeCodecFactory = new UpgradeCodecFactory() {
+            @Override
+            public UpgradeCodec newUpgradeCodec(CharSequence protocol) {
+                return new Http2ServerUpgradeCodec(http2Codec);
+            }
+        };
+        http2ConnectionHandler = http2Codec.frameCodec().connectionHandler();
+
+        userEvents = new ArrayList<Object>();
+
+        HttpServerCodec httpServerCodec = new HttpServerCodec();
+        HttpServerUpgradeHandler upgradeHandler = new HttpServerUpgradeHandler(httpServerCodec, upgradeCodecFactory);
+
+        CleartextHttp2ServerUpgradeHandler handler = new CleartextHttp2ServerUpgradeHandler(
+                httpServerCodec, upgradeHandler, http2Codec);
+        channel = new EmbeddedChannel(handler, new ChannelInboundHandlerAdapter() {
+            @Override
+            public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
+                userEvents.add(evt);
+            }
+        });
+
+        assertFalse(channel.writeInbound(Http2CodecUtil.connectionPrefaceBuf()));
+
+        ByteBuf settingsFrame = settingsFrameBuf();
+
+        assertFalse(channel.writeInbound(settingsFrame));
+
+        assertEquals(1, userEvents.size());
+        assertTrue(userEvents.get(0) instanceof PriorKnowledgeUpgradeEvent);
+    }
+
     private static ByteBuf settingsFrameBuf() {
         ByteBuf settingsFrame = Unpooled.buffer();
         settingsFrame.writeMedium(12); // Payload length