map<TResult extends Object?>  method 
- @optionalTypeArgs
- required TResult threadItemPost(- UThreadItemValueThreadItemPost value
 
- required TResult unknown(- UThreadItemValueUnknown value
 
A switch-like method, using callbacks.
Callbacks receives the raw object, upcasted. It is equivalent to doing:
switch (sealedClass) {
  case final Subclass value:
    return ...;
  case final Subclass2 value:
    return ...;
}
Implementation
@optionalTypeArgs TResult map<TResult extends Object?>({required TResult Function( UThreadItemValueThreadItemPost value)  threadItemPost,required TResult Function( UThreadItemValueUnknown value)  unknown,}){
final _that = this;
switch (_that) {
case UThreadItemValueThreadItemPost():
return threadItemPost(_that);case UThreadItemValueUnknown():
return unknown(_that);}
}