Major Description
Checking how _firstRequestProcessed works, I notice we can do some enhancements LifecycleImpl and LifecycleFactoryImpl. In both classes, we use synchronized blocks to access common methods, but that is not really necessary, we can do other alternatives like ConcurrentHashMap and CopyOnWriteArrayList and they will be more effective.
Note LifecycleImpl instance is shared by multiple threads at the same time, so it must be thread safe. If we have variables that changes inside it, we must ensure visibility adding "final" and "volatile" modifiers too when necessary.