code: public static InputStream inputStreamForResponse(InputStream is, ProgressListener progressListener) {
          return progressListener == null
                  ? is
                  : new ResponseProgressInputStream(is, progressListener);
      }
docs: Returns an input stream for response progress tracking purposes. If request/response progress tracking is not enabled, this
  method simply return the given input stream as is.
  
  @param is               the response content input stream
  @param progressListener Optional progress listener
  @return If the progress listener is non null returns a new input stream decorated with progress reporting functionality. If
  progress listener is null it returns the same input stream.