public function triggerEvent($event, Payload $payload)
    {
        if ($payload->state() === null) {
            $this->updatePayload($this->process->initialState(), $payload);
        }

        $state = $this->process->state($payload->state());

        $nextStateName = $state->triggerEvent($event, $payload);
        if ($nextStateName === null) {
            return;
        }

        $state = $this->process->state($nextStateName);

        $this->updatePayload($state, $payload);
        $this->handleOnStateWasSet($state, $payload);
    }