private void buildChildren() {
    if (children == null) {
      final List<M> callers = findCallers();
      //noinspection UseOfObsoleteCollectionType
      children = new Vector<>(callers.size());
      for (M caller : callers) {
        final HashSet<M> called = new HashSet<>(myCalled);
        called.add(getMember());
        final MemberNodeBase<M> child = createNode(caller, called);
        children.add(child);
        child.parent = this;
      }
    }
  }
private void buildChildren()