}

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

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

    // an immutable list, which would change the behavior of this method
    return asCharSource(file, charset)
        .readLines(
            new LineProcessor<List<String>>() {
              final List<String> result = new ArrayList<>();

              @Override
              public boolean processLine(String line) {
                result.add(line);

   * @since 14.0
   */
  @CanIgnoreReturnValue // some processors won't return a useful result
  @ParametricNullness
  public static <T extends @Nullable Object> T readLines(
      Readable readable, LineProcessor<T> processor) throws IOException {
    checkNotNull(readable);
    checkNotNull(processor);

    LineReader lineReader = new LineReader(readable);
    String line;

    // an immutable list, which would change the behavior of this method
    return asCharSource(file, charset)
        .readLines(
            new LineProcessor<List<String>>() {
              final List<String> result = new ArrayList<>();

              @Override
              public boolean processLine(String line) {
                result.add(line);