@Nullable Set<T> getMemberDependencies(T member) {
    Set<T> result = myDependencyGraph.get(member);
    if (result == null) {
      DependentMembersCollectorBase<T, C> collector = getCollector(member);
      if (collector != null) {
        collector.collect(member);
        result = collector.getCollection();
      }
      myDependencyGraph.put(member, result);
    }
    return result;
  }
@Nullable Set<T> getMemberDependencies(T member)