/**
  * Set outgoing message class. Should not be used together setOutgoingMessageClasses (throws
  * exception if called with it), as it is unnecessary to do so.
  *
  * @param outgoingMessageClass outgoing message class
  */
 public void setOutgoingMessageClass(Class<? extends Writable> outgoingMessageClass) {
   Preconditions.checkState(outgoingMessageClasses instanceof DefaultMessageClasses);
   ((DefaultMessageClasses) outgoingMessageClasses).setMessageClass(outgoingMessageClass);
 }
 /**
  * Set message combiner class. Should not be used together setOutgoingMessageClasses (throws
  * exception if called with it), as it is unnecessary to do so.
  *
  * @param messageCombinerClass message combiner class
  */
 public void setMessageCombinerClass(Class<? extends MessageCombiner> messageCombinerClass) {
   Preconditions.checkState(outgoingMessageClasses instanceof DefaultMessageClasses);
   ((DefaultMessageClasses) outgoingMessageClasses).setMessageCombinerClass(messageCombinerClass);
 }