Allow any annotation named "Open"

[JakeWharton]

We shouldn't enforce the use of our annotation artifact

[kalgon]

Could we give other annotations in parameters which should be treated like @Open? I am thinking of classes annotated with @XXXScoped in Spring/CDI or @Entity in JPA (for lazy-loading) which often need to be proxied (and thus need to be non-final).

[JakeWharton]

I don't write any Java anymore, but I'd take a PR for support of a list of custom annotation qualified names.