code: public boolean compareAndSetChannel(@Nullable Channel oldChannel, @Nullable Channel newChannel) {
          return channel.compareAndSet(oldChannel, newChannel);
      }
docs: Set the {@link Channel} used to communicate with the Raft server
  to {@code newChannel} <strong>only if</strong> the current channel is {@code oldChannel}.
  noop otherwise.
  
  @param oldChannel expected value of the {@code Channel}
  @param newChannel a valid, <strong>connected</strong>d {@code Channel} to the Raft server.
  {@code null} if no connection exists
  @return true if the value was set to {@code newChannel}, false otherwise