private static Iterable<LookupElement> withoutInitial(Iterable<? extends LookupElement> allItems, List<? extends LookupElement> initial) {
      Set<LookupElement> initialSet = new ReferenceOpenHashSet<>(initial);
      return JBIterable.<LookupElement>from(allItems).filter(element -> !initialSet.contains(element));
    }
private static Iterable<LookupElement> withoutInitial(Iterable<? extends LookupElement> allItems, List<? extends LookupElement> initial)