public Set<String> intersectKeys(@Nullable Set<String> names2Include) {
    if (myAll != null) {
      if (names2Include == null) return myAll.keySet();
      return SetUtil.intersect(names2Include, myAll.keySet());
    }
    if (myK != null && (names2Include == null || names2Include.contains(myK))) {
      if (names2Include != null && names2Include.size() == 1) return names2Include;
      final HashSet<String> result = new HashSet<>();
      result.add(myK);
      return result;
    }
    return Collections.emptySet();
  }
public Set<String> intersectKeys(@Nullable Set<String> names2Include)