class PushNotificationSubscriptionServiceImpl implements PushNotificationSubscriptionService {

    @Nonnull
    @Override
    public boolean checkIfPushNotificationSubscriptionExistsForUser(@Nonnull final Long userId) {
        assertUserIdNotNull(userId);
        LOGGER.debug("Checking if push notification subscription exists for user with id - {}", userId);
        final User user = userService.getUserById(userId);
        final PushNotificationSubscription subscription = pushNotificationSubscriptionRepository.findByUser(user);
        final boolean exists = (subscription != null);
        LOGGER.debug("Push notification subscription lookup result for user with id - {} is - {}", userId, exists);
        return exists;
    }

    public  PushNotificationSubscriptionServiceImpl();

}