Right; I don't think there's any harm…unless you're trying to have an observer method elsewhere notify your JpaInjectionServices implementation.

The JpaInjectionServices implementation is not a bean, and so putting an observer method in it doesn't work. So I made a bean to house the observer method. I wanted the observer method to tell the JpaInjectionServices instance that an event has arrived. To do this, I created an Extension that adds the JpaInjectionServices instance as a singleton bean. That was when I discovered it was being created three times.

At any rate it might be worth a note somewhere that there is no guarantee about the number of times your Service implementation will be instantiated.