@Override
  public long getSize() {
    return 1;
  }
Create an instance of {@link IncompleteReadReadableStreamChannel} with {@code bytesRead} and
{@code exceptionToThrow} that will be returned via the future and callback.
@param bytesRead The number of bytes read that needs to be returned. Can be null.
@param exceptionToThrow if desired, provide an exception that will thrown on read. Can be null.
ambry-rest/src/test/java/com/github/ambry/rest/AsyncRequestResponseHandlerTest.java