@NotNull
  private static List<GrLiteral> collectOperands(@Nullable PsiElement element, @NotNull List<GrLiteral> initial) {
    if (element instanceof GrLiteral) {
      initial.add((GrLiteral)element);
    }
    else if (element instanceof GrBinaryExpression) {
      collectOperands(((GrBinaryExpression)element).getLeftOperand(), initial);
      collectOperands(((GrBinaryExpression)element).getRightOperand(), initial);
    }
    return initial;
  }
@NotNull
  private static List<GrLiteral> collectOperands(@Nullable PsiElement element, @NotNull List<GrLiteral> initial)