As discussed in #42, the naming is a bit off. Rename in the component and the bundle. This will be a hard BC break of course. If we can merge the nginx PR first, we could do the change in one go, otherwise we break it again.

for using in the bundle, i think it makes sense to have a proxy_client.varnish and other proxy_client.X and then define the alias from the DI class for default_proxy_client. that way some really complicated setup could even run both varnish and nginx or symfony built-in cache clients, and add his own services with the other clients.