@Override
  protected PsiElement[] getVariables(Expression[] params, ExpressionContext context) {
    final PsiElement[] variables = super.getVariables(params, context);
    if (variables == null) return null;
    final List<PsiElement> result = new ArrayList<>();
    final List<String> skip = Arrays.asList("true", "false", "this", "super");
    for (PsiElement variable : variables) {
      if (!skip.contains(variable.getText())) {
        result.add(variable);
      }
    }
    return PsiUtilCore.toPsiElementArray(result);
  }
@Override
  protected PsiElement[] getVariables(Expression[] params, ExpressionContext context)