Move VoidEnum to util

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocket00FrameDecoder.java

@@ -20,7 +20,7 @@ import io.netty.channel.Channel;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.ReplayingDecoder;
 import io.netty.handler.codec.TooLongFrameException;
-import io.netty.handler.codec.VoidEnum;
+import io.netty.util.VoidEnum;
 
 /**
  * Decodes {@link ChannelBuffer}s into {@link WebSocketFrame}s.

codec/src/main/java/io/netty/handler/codec/MessageToMessageDecoder.java

@@ -30,9 +30,9 @@ public abstract class MessageToMessageDecoder<I, O> extends ChannelInboundHandle
 
                 O emsg = decode(ctx, msg);
                 if (emsg == null) {
-                    throw new IllegalArgumentException(
-                            "decode() returned null. unsupported message type? " +
-                            msg.getClass().getName());
+                    // Decoder consumed a message but returned null.
+                    // Probably it needs more messages.
+                    continue;
                 }
 
                 if (unfoldAndAdd(ctx, ctx.nextIn(), emsg)) {

codec/src/main/java/io/netty/handler/codec/ReplayingDecoder.java

@@ -26,6 +26,7 @@ import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInboundHandlerContext;
 import io.netty.channel.ChannelPipeline;
 import io.netty.util.Signal;
+import io.netty.util.VoidEnum;
 
 /**
  * A specialized variation of {@link StreamToMessageDecoder} which enables implementation

codec/src/main/java/io/netty/handler/codec/redis/RedisDecoder.java

@@ -19,7 +19,7 @@ import io.netty.buffer.ChannelBuffer;
 import io.netty.buffer.ChannelBufferIndexFinder;
 import io.netty.channel.ChannelInboundHandlerContext;
 import io.netty.handler.codec.ReplayingDecoder;
-import io.netty.handler.codec.VoidEnum;
+import io.netty.util.VoidEnum;
 
 import java.io.IOException;
 

codec/src/test/java/io/netty/handler/codec/ReplayingDecoderTest.java

@@ -21,6 +21,7 @@ import io.netty.buffer.ChannelBufferIndexFinder;
 import io.netty.buffer.ChannelBuffers;
 import io.netty.channel.ChannelInboundHandlerContext;
 import io.netty.handler.codec.embedder.DecoderEmbedder;
+import io.netty.util.VoidEnum;
 
 import org.junit.Test;
 

common/src/main/java/io/netty/util/VoidEnum.java

@@ -13,12 +13,11 @@
  * License for the specific language governing permissions and limitations
  * under the License.
  */
-package io.netty.handler.codec;
+package io.netty.util;
+
 
 /**
- * A placeholder {@link Enum} which could be specified as a type parameter of
- * {@link ReplayingDecoder} when a user wants to manage the decoder state or
- * there's no state to manage.
+ * A place holder {@link Enum} which has no constant.
  */
 public enum VoidEnum {
     // No state is defined.