return new byte[BUFFER_SIZE];
  }

  /**
   * There are three methods to implement {@link FileChannel#transferTo(long, long,
   * WritableByteChannel)}:
   *
   * <ol>
   *   <li>Use sendfile(2) or equivalent. Requires that both the input channel and the output
   *       channel have their own file descriptors. Generally this only happens when both channels

        final int sizeThreshold = getSizeThreshold();
        final File repository = createRepositoryFile();
        return DiskFileItemFactory.builder().setBufferSize(sizeThreshold).setFile(repository).get();
    }

    protected int getSizeThreshold() {
        return ComponentUtil.getFessConfig().getHttpFileuploadThresholdSizeAsInteger();
    }

    protected File createRepositoryFile() {

    setUp(parameters.first, parameters.second)
    val editor = cache.edit("k1")!!
    editor.setString(0, "ABC")
    editor.setString(1, "B")
    editor.commit()
    val k1 = getCleanFile("k1", 0)
    assertThat(readFile(k1)).isEqualTo("ABC")
    cache.remove("k1")
    assertThat(filesystem.exists(k1)).isFalse()
  }

  @ParameterizedTest
  @ArgumentsSource(FileSystemParamProvider::class)