Fixes https://github.com/spring-projects/spring-integration/issues/3169 All other `DefaultSessionFactoryLocator` contracts are based on the `Object`, so this `addSessionFactor`y has to be on `Object` as well. * Add `DefaultSessionFactoryLocator.addSessionFactory(Object key, SessionFactory<F> factory)` * Deprecate existing one based on `String` * Fix tests do no use a deprecated API * Some other code style clean up in the affected classes **Cherry-pick to 5.2.x**