Refactoring, dropped unuseful ServerChannel abstraction in favor on Netty's Channel

broker/src/test/java/io/moquette/spi/impl/MockReceiverChannel.java

@@ -16,7 +16,6 @@
 
 import io.netty.util.AttributeKey;
 import io.moquette.proto.messages.AbstractMessage;
-import io.moquette.server.ServerChannel;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -24,7 +23,7 @@ import java.util.Map;
 /**
  * This a synchronous channel that avoid output ring buffer from Processor
  */
-class MockReceiverChannel implements ServerChannel {
+class MockReceiverChannel /*implements ServerChannel*/ {
     //        byte m_returnCode;
     AbstractMessage m_receivedMessage;
     private Map<Object, Object> m_attributes = new HashMap<>();