ARTEMIS-5249 support WebSocket pong frames

The broker should simply receive WebSocket pong frames and not respond
according to section 5.5.3 of RFC 6455 (i.e. the WebSocket Protocol
specification).

artemis-server/src/main/java/org/apache/activemq/artemis/core/server/protocol/websocket/WebSocketServerHandler.java

@@ -113,6 +113,8 @@ private boolean handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame f
       } else if (frame instanceof PingWebSocketFrame) {
          ctx.writeAndFlush(new PongWebSocketFrame(frame.content().retain()));
          return false;
+      } else if (frame instanceof PongWebSocketFrame) {
+         return false;
       } else if (!(frame instanceof TextWebSocketFrame) && !(frame instanceof BinaryWebSocketFrame) && !(frame instanceof ContinuationWebSocketFrame)) {
          throw new UnsupportedOperationException(String.format("%s frame types not supported", frame.getClass().getName()));
       }

artemis-server/src/test/java/org/apache/activemq/artemis/core/server/protocol/websocket/WebSocketServerHandlerTest.java

@@ -16,24 +16,25 @@
  */
 package org.apache.activemq.artemis.core.server.protocol.websocket;
 
-import static org.mockito.Mockito.any;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.spy;
-import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.verifyNoMoreInteractions;
-
 import java.util.Arrays;
 import java.util.List;
 
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.extension.ExtendWith;
-import org.mockito.junit.jupiter.MockitoExtension;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.http.websocketx.BinaryWebSocketFrame;
 import io.netty.handler.codec.http.websocketx.ContinuationWebSocketFrame;
+import io.netty.handler.codec.http.websocketx.PongWebSocketFrame;
 import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import static org.mockito.Mockito.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 /**
  * WebSocketServerHandlerTest
@@ -76,6 +77,17 @@ public void testRead0HandleBinaryFrame() throws Exception {
       verifyNoMoreInteractions(spy, ctx);
    }
 
+   @Test
+   public void testRead0HandlePongFrame() throws Exception {
+      ChannelHandlerContext ctx = mock(ChannelHandlerContext.class);
+      Object msg = new PongWebSocketFrame();
+
+      spy.channelRead0(ctx, msg);
+
+      verify(spy).channelRead0(ctx, msg);
+      verifyNoMoreInteractions(spy, ctx);
+   }
+
    @Test
    public void testRead0HandleTextFrame() throws Exception {
       ChannelHandlerContext ctx = mock(ChannelHandlerContext.class);