whenOrNull<TResult extends Object?> method

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>(TResult? $default(String? getepayTxnId, String? mid, String? txnAmount, String? txnStatus, String? merchantOrderNo, String? udf1, String? udf2, String? udf3, String? udf4, String? udf5, String? udf6, String? udf7, String? udf8, String? udf9, String? udf10, String? udf41, String? custRefNo, String? paymentMode, String? currency, String? discriminator, String? message, String? paymentStatus, DateTime? txnDate, String? surcharge, String? totalAmount, String? settlementAmount, String? settlementRefNo, String? settlementDate, String? txnNote,)?)

A variant of when that fallback to returning null

It is equivalent to doing:

switch (sealedClass) {
  case Subclass(:final field):
    return ...;
  case _:
    return null;
}

Implementation

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>(TResult? Function( String? getepayTxnId,  String? mid,  String? txnAmount,  String? txnStatus,  String? merchantOrderNo,  String? udf1,  String? udf2,  String? udf3,  String? udf4,  String? udf5,  String? udf6,  String? udf7,  String? udf8,  String? udf9,  String? udf10,  String? udf41,  String? custRefNo,  String? paymentMode,  String? currency,  String? discriminator,  String? message,  String? paymentStatus,  DateTime? txnDate,  String? surcharge,  String? totalAmount,  String? settlementAmount,  String? settlementRefNo,  String? settlementDate,  String? txnNote)?  $default,) {final _that = this;
switch (_that) {
case _PgInvoiceResponse() when $default != null:
return $default(_that.getepayTxnId,_that.mid,_that.txnAmount,_that.txnStatus,_that.merchantOrderNo,_that.udf1,_that.udf2,_that.udf3,_that.udf4,_that.udf5,_that.udf6,_that.udf7,_that.udf8,_that.udf9,_that.udf10,_that.udf41,_that.custRefNo,_that.paymentMode,_that.currency,_that.discriminator,_that.message,_that.paymentStatus,_that.txnDate,_that.surcharge,_that.totalAmount,_that.settlementAmount,_that.settlementRefNo,_that.settlementDate,_that.txnNote);case _:
  return null;

}
}