Confusion over prefetching

[calbro7]

Hi, I'm a bit confused by the sample code in the prefetching section of the docs:

#[Type]
class PostType {
    /**
     * @param Post $post
     * @param mixed $prefetchedUsers
     * @return User
     */
    #[Field(prefetchMethod: "prefetchUsers")]
    public function getUser(Post $post, $prefetchedUsers): User
    {
        // This method will receive the $prefetchedUsers as second argument. This is the return value of the "prefetchUsers" method below.
        // Using this prefetched list, it should be easy to map it to the post
    }

    /**
     * @param Post[] $posts
     * @return mixed
     */
    public function prefetchUsers(iterable $posts)
    {
        // This function is called only once per GraphQL request
        // with the list of posts. You can fetch the list of users
        // associated with this posts in a single request,
        // for instance using a "IN" query in SQL or a multi-fetch
        // in your cache back-end.
    }
}

The class is PostType but all the type annotations are for Post. Is this a mistake and the types are supposed to match up? Or else what is Post?