Merge "Protect callbacks from concurrent modification" into main

    override fun transitionTo(oldState: DozeMachine.State, newState: DozeMachine.State) {

        this.oldState = oldState

        this.newState = newState

        callbacks.forEach { it.onDozeTransition(oldState, newState) }

        val cbs = synchronized(this) { callbacks.toSet() }

        cbs.forEach { it.onDozeTransition(oldState, newState) }

    }

    override fun addCallback(callback: DozeTransitionCallback) {

        callbacks.add(callback)

        synchronized(this) { callbacks.add(callback) }

    }

    override fun removeCallback(callback: DozeTransitionCallback) {

        callbacks.remove(callback)

        synchronized(this) { callbacks.remove(callback) }

    }

}