@WithStateMachine annotation can be used to associate a state machine with a existing bean. Within this annotation a property’s source and target can be used to qualify a transition

@WithStateMachine
static class Bean1 {

    @OnTransition(source = "S1", target = "S2")
    public void fromS1ToS2() {
    }
}

Default @OnTransition annotation can’t be used with a state and event enums user have created due to java language limitations, thus string representation have to be used.

However if you want to have a type safe annotation it is possible to create a new annotation and use @OnTransition as meta annotation. This user level annotation can make a reference to actual states and events enums and framework will try to match these in a same way.

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@OnTransition
static @interface StatesOnTransition {

    States[] source() default {};

    States[] target() default {};
}

Above we created a @StatesOnTransition annotation which defines source and target as a type safe manner.

@WithStateMachine
static class Bean2 {

    @StatesOnTransition(source = States.S1, target = States.S2)
    public void fromS1ToS2() {
    }
}

In your own bean you can then use this @StatesOnTransition as is and use type safe source and target.