code: public void pauseUpload() throws LocalOperationException {
          if (state == State.UPLOADING) {
              setState(State.PAUSED);
              executor.hardStop();
          } else {
              throw new LocalOperationException("Attempt to pause upload while assembly is not uploading");
          }
      }
docs: Pauses the file upload. This is a blocking function that would try to wait till the assembly file uploads
  have actually been paused if possible.
  
  @throws LocalOperationException if the method is called while no upload is going on.