* @param callback the LineProcessor to use to handle the lines
   * @return the output of processing the lines
   * @throws IOException if an I/O error occurs
   */
  @CanIgnoreReturnValue // some processors won't return a useful result
  @ParametricNullness
  public static <T extends @Nullable Object> T readLines(
      URL url, Charset charset, LineProcessor<T> callback) throws IOException {

    }
  }

  public void testReadLines_withProcessor() throws IOException {
    List<String> list =
        source.readLines(
            new LineProcessor<List<String>>() {
              final List<String> list = new ArrayList<>();

              @Override
              public boolean processLine(String line) throws IOException {
                list.add(line);

  }

  public void testReadLines_withLineProcessor() throws IOException {
    URL resource = getClass().getResource("testdata/alice_in_wonderland.txt");
    LineProcessor<List<String>> collectAndLowercaseAndTrim =
        new LineProcessor<List<String>>() {
          final List<String> collector = new ArrayList<>();

          @Override
          public boolean processLine(String line) {