maybeWhen<TResult extends Object?>  method 
- @optionalTypeArgs
A variant of when that fallback to an orElse callback.
It is equivalent to doing:
switch (sealedClass) {
  case Subclass(:final field):
    return ...;
  case _:
    return orElse();
}
Implementation
@optionalTypeArgs TResult maybeWhen<TResult extends Object?>(TResult Function( String transferTo,  String amount,  String tokenContract,  String symbol,  int decimals)?  $default,{required TResult orElse(),}) {final _that = this;
switch (_that) {
case _InitialTransactionMetadataCompat() when $default != null:
return $default(_that.transferTo,_that.amount,_that.tokenContract,_that.symbol,_that.decimals);case _:
  return orElse();
}
}