BusProvider as enum

BusProvider.java

public final enum BusProvider {
    INSTANCE;
  
    public final Bus BUS;

	private BusProvider() {
		BUS = new Bus();
	}
}

CallBus.java

BusProvider.INSTANCE.BUS;
// or do something useful with it:
BusProvider.INSTANCE.BUS.post(someObj);

CallMultiBus.java

MultiBusProvider.BUS_ONE.BUS;
MultiBusProvider.BUS_TWO.BUS;
// or do something useful with it:
MultiBusProvider.BUS_ONE.BUS.post(someObj);
MultiBusProvider.BUS_TWO.BUS.post(anotherObj);

MultiBusProvider.java

public final enum MultiBusProvider {
    BUS_ONE, BUS_TWO;
  
    public final Bus BUS;

	private MultiBusProvider() {
		BUS = new Bus();
	}
}