public Stream<String> lines() {
      return stream(linesIterator());
    }

    @Override
    public @Nullable String readFirstLine() {
      Iterator<String> lines = linesIterator();
      return lines.hasNext() ? lines.next() : null;
    }

    @Override
    public ImmutableList<String> readLines() {
      return ImmutableList.copyOf(linesIterator());
    }

    @Override
    @ParametricNullness