Lifecycle OnLifecycleEvent is deprecated

[marawanxmamdouh]

It's deprecated because they now expect you to use Java 8 and implement the interface DefaultLifecycleObserver. Since Java 8 allows interfaces to have default implementations, they defined DefaultLifecycleObserver with empty implementations of all the methods so you only need to override the ones you use.

The old way of marking functions with @OnLifecycleEvent was a crutch for pre-Java 8 projects. This was the only way to allow a class to selectively choose which lifecycle events it cared about. The alternative would have been to force those classes to override all the lifecycle interface methods, even if leaving them empty.