private static @Nullable String getClosureContents(int rangeStart, int rangeEnd, @NotNull CharSequence seq) {
    int firstLineStart = CharArrayUtil.shiftForward(seq, rangeStart, " \t");
    if (firstLineStart < seq.length() - 1 && seq.charAt(firstLineStart) == '\n') firstLineStart++;

    int lastLineEnd = CharArrayUtil.shiftBackward(seq, rangeEnd - 1, " \t");
    if (lastLineEnd > 0 && seq.charAt(lastLineEnd) == '\n') lastLineEnd--;
    if (lastLineEnd < firstLineStart) return null;
    return seq.subSequence(firstLineStart, lastLineEnd).toString();
  }
private static @Nullable String getClosureContents(int rangeStart, int rangeEnd, @NotNull CharSequence seq)