private static @Nullable ASTNode findFirstLeaf(ASTNode first, ASTNode last) {
    do {
      LeafElement leaf = TreeUtil.findFirstLeaf(first);
      if (leaf != null) return leaf;
      first = first.getTreeNext();
      if (first == null) return null;
    }
    while (first != last);
    return null;
  }
private static @Nullable ASTNode findFirstLeaf(ASTNode first, ASTNode last)