@Override
  public void close() throws IOException {
    channelOpen.set(false);
  }
Either throws the exception provided or returns immediately saying no bytes were read.
@param asyncWritableChannel the {@link AsyncWritableChannel} to read the data into.
@param callback the {@link Callback} that will be invoked either when all the data in the channel has been emptied
                into the {@code asyncWritableChannel} or if there is an exception in doing so. This can be null.
@return a {@link Future} that will eventually contain the result of the operation.
ambry-rest/src/test/java/com/github/ambry/rest/AsyncRequestResponseHandlerTest.java