whenOrNull<TResult extends Object?>  method 
- @optionalTypeArgs
- TResult? $default(- List<Ed25519HDPublicKey> writable,
- List<Ed25519HDPublicKey> readonly
 
- List<
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( List<Ed25519HDPublicKey> writable,  List<Ed25519HDPublicKey> readonly)?  $default,) {final _that = this;
switch (_that) {
case _LoadedAddresses() when $default != null:
return $default(_that.writable,_that.readonly);case _:
  return null;
}
}