static @Nullable Set<TaintNode> getSelectedElements(@NotNull TaintNode taintNode,
                                                      @NotNull Set<TaintNode> nodes) {
    if (taintNode.getPsiElement() == null) return null;
    if (taintNode.isExcluded()) return nodes;
    nodes.add(taintNode);
    List<TaintNode> children = taintNode.calcChildren();
    if (children == null) return nodes;
    for (TaintNode child : children) {
      if (getSelectedElements(child, nodes) == null) return null;
    }
    return nodes;
  }
static @Nullable Set<TaintNode> getSelectedElements(@NotNull TaintNode taintNode,
                                                      @NotNull Set<TaintNode> nodes)