Summary: This deprecates the `getPlugin(String)` method and introduces a `getPluginByClass(Class<T>)` instead which avoids having to `instanceof`-check and then cast the result, which provides a nicer experience for Java users. Reviewed By: jknoxville Differential Revision: D13277568 fbshipit-source-id: fb7b5b8c0180470ef0ad322559b5b7424520848b