Java generics - ? vs Object

Question

So I have the following class

public abstract class DeliveryFileType<T> {        
    public abstract Stream<T> getStream();
    
    public abstract ArrayList<String> processRecordToArrayList(T t);    
}

Then the code

DeliveryFileType<?> deliveryFileType = DeliveryFileTypeFactory.createDeliveryType(deliveryFileStore, delivery.getFileLocation());

Flowable<ArrayList<String>> recordStream = Flowable.fromStream(deliveryFileType.getStream()).map(record -> deliveryFileType.processRecordToArrayList(record));

This createDeliveryType returns a DeliveryFileType<?>, in which depending on the parameter it can return diffent types, e.g., DeliveryFileType<String>, DeliveryFileType<Map<String, String>>, etc.

With this code, Java complains java.lang.Object cannot be converted to capture of ? referring to record on deliveryFileType.processRecordToArrayList(record) in the second line.

Why does this happen? The method getStream return an stream of elements T, so record should also be from the same type T, not Object.

If I change the code declaration in the first snippet to:

DeliveryFileType<Object> deliveryFileType = ...

and the method createDeliveryType in the factory to return a DeliveryFileType, instead of DeliveryFileType<?>, the error goes away.

This question is similar, but it doesn't answer my quetion, because I'm not talking about subtypes here. Java generics, Unbound wildcards <?> vs <Object>