@Override
  public boolean isOpen() {
    return channelOpen.get();
  }
If the channel is open, simply queues the buffer to be handled later.
@param src the data that needs to be written to the channel.
@param callback the {@link Callback} that will be invoked once the write succeeds/fails. This can be null.
@return a {@link Future} that will eventually contain the result of the write operation.
@throws IllegalArgumentException if {@code src} is null.
ambry-test-utils/src/main/java/com/github/ambry/router/ByteBufferAWC.java