code: @Override
      public AsyncInputStream resume() {
          switch (state) {
              case STATUS_CLOSED:
                  throw new IllegalStateException("Cannot resume, already closed");
              case STATUS_PAUSED:
                  state = STATUS_ACTIVE;
                  doRead();
          }
          return this;
      }
docs: Resumes the reading.
  
  @return the current {@code AsyncInputStream}