When talking about the decorator pattern outside of Symfony, the terminner is pretty much (if not totally) inexistent. Worse, it makes the concept harder to explain. Take "there is a decorator and a decorated object" vs "there is a decorator and an inner object": using the later form, one has to explain both what is the decorator and what is the inner. While using the former, explaining what the decorator makes it obvious what the decorated is.

I propose to take the addition of this attribute as an opportunity to start making this special term go away.

Also I removed theService suffix. It is tempting to keep it for explicitness, but it feels kinda redundant and AFAIK no other core attribute has such redundant suffix, maybe because their namespace is enough to indicate their target.