long bytesRead = super.read(sink, byteCount);
          // read() returns the number of bytes read, or -1 if this source is exhausted.
          totalBytesRead += bytesRead != -1 ? bytesRead : 0;
          progressListener.update(totalBytesRead, responseBody.contentLength(), bytesRead == -1);
          return bytesRead;
        }
      };
    }
  }