public static boolean containsWhiteSpacesOnly(@Nullable ASTNode node) {
    if (node == null) return false;

    ArrayDeque<ASTNode> queue = new ArrayDeque<>();
    queue.offer(node);
    while (!queue.isEmpty()) {
      TreeElement each = (TreeElement)queue.poll();
      if (each instanceof CompositeElement && spacesOnly(each)) {
        continue;
      }

      if (each instanceof LeafElement && !spacesOnly(each)) {
        return false;
      }

      Collections.addAll(queue, each.getChildren(null));
    }
    return true;
  }
public static boolean containsWhiteSpacesOnly(@Nullable ASTNode node)