Set<String> (@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(); }