@Override
  @Nullable
  public LookupEx showLookup(@NotNull final Editor editor,
                           LookupElement @NotNull [] items,
                           @NotNull final String prefix,
                           @NotNull final LookupArranger arranger) {
    for (LookupElement item : items) {
      assert item != null;
    }

    LookupImpl lookup = createLookup(editor, items, prefix, arranger);
    return lookup.showLookup() ? lookup : null;
  }
@Override
  @Nullable
  public LookupEx showLookup(@NotNull final Editor editor,
                           LookupElement @NotNull [] items,
                           @NotNull final String prefix,
                           @NotNull final LookupArranger arranger)