validateMandatoryRequirement method

String? validateMandatoryRequirement()

Implementation

String? validateMandatoryRequirement() {
  if (gstController.text.isEmpty &&
      panController.text.isEmpty &&
      aadharController.text.isEmpty) {
    return 'At least one (GST, PAN, or Aadhar) is mandatory.';
  }
  return null;
}