How to return a null from a mapper if a condition is met

Question

I want to return null from my mapper method if a complex condition is met, but mapstruct ignores null value returned from @AfterMapping method, so How can I achieve this?

The code below has comments that demonstrate what I need

class User{
    String name;
    Role role;
    Date birthDate;
}

@Mapper(componentModel = "spring")
interface UserMapper{
    Inner toUser(Source source);
    /* I want to return a null user depending on a complex condition
    *  However, mapstruct ingores null value returned from the following @AfterMapping method
    * */
    
    @AfterMapping
    default User checkUser(@MappingTarget User user){
        // return null or not depending on a complex condition
        if(condition)
            return null;
        else return user;
    }
}

Answer 1

You can use a decorator:

Official documentation: Customizing mappings with Decorator
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