static PsiElement[] getOccurrences(GrIntroduceParameterSettings settings) {
    final GrParameterListOwner scope = settings.getToReplaceIn();

    final GrExpression expression = settings.getExpression();
    if (expression != null) {
      final PsiElement expr = PsiUtil.skipParentheses(expression, false);
      if (expr == null) return PsiElement.EMPTY_ARRAY;

      final PsiElement[] occurrences = GroovyRefactoringUtil.getExpressionOccurrences(expr, scope);
      if (occurrences.length == 0) {
        throw new GrRefactoringError(GroovyRefactoringBundle.message("no.occurrences.found"));
      }
      return occurrences;
    }
    else {
      final GrVariable var = settings.getVar();
      LOG.assertTrue(var != null);
      final List<PsiElement> list = Collections.synchronizedList(new ArrayList<>());
      ReferencesSearch.search(var, new LocalSearchScope(scope)).forEach(psiReference -> {
        list.add(psiReference.getElement());
        return true;
      });
      return list.toArray(PsiElement.EMPTY_ARRAY);
    }
  }
static PsiElement[] getOccurrences(GrIntroduceParameterSettings settings)