Property Mapper should be able to map to target if only a setter exists
The property mapper checks if it can set a certain property in the target by consulting the Class Schema of the target class. This assumes that a class property of the same name must exist in order to set a property.
However, we use the ObjectAccess API to ultimately set the property which does not require such class property. It could easily be that only a setter method exists which stores the property somewhere else and this should be sufficient to map the property.
Therefore the map function needs to be refactored to use information from ObjectAccess::isPropertySettable / isPropertyGettable instead of relying on the class schema.