@Override
  public LookupElement[] calculateLookupItems(Expression @NotNull [] params, ExpressionContext context) {
    if (params.length ==0) return null;
    Set<LookupElement> set = new LinkedHashSet<>();

    for (Expression param : params) {
      Result object = param.calculateResult(context);
      if (object != null) {
        set.add(LookupElementBuilder.create(object.toString()));
      }
    }
    return set.toArray(LookupElement.EMPTY_ARRAY);
  }
@Override
  public LookupElement[] calculateLookupItems(Expression @NotNull [] params, ExpressionContext context)