pocketmine\entity\Entity::registerEntity PHP Method

    public static function registerEntity($className, $force = false)
    {
        $class = new \ReflectionClass($className);
        if (is_a($className, Entity::class, true) and !$class->isAbstract()) {
            if ($className::NETWORK_ID !== -1) {
                self::$knownEntities[$className::NETWORK_ID] = $className;
            } elseif (!$force) {
                return false;
            }
            self::$knownEntities[$class->getShortName()] = $className;
            self::$shortNames[$className] = $class->getShortName();
            return true;
        }
        return false;
    }

 public function onEnable()
 {
     $this->hitSessions = [];
     Entity::registerEntity(SlapperCreeper::class, true);
     Entity::registerEntity(SlapperBat::class, true);
     Entity::registerEntity(SlapperSheep::class, true);
     Entity::registerEntity(SlapperPigZombie::class, true);
     /*Entity::registerEntity(SlapperGhast::class,true);
     		Entity::registerEntity(SlapperIronGolem::class,true);
     		Entity::registerEntity(SlapperSnowman::class,true);
     		Entity::registerEntity(SlapperOcelot::class,true);
     		*/
     Entity::registerEntity(SlapperHuman::class, true);
     Entity::registerEntity(SlapperVillager::class, true);
     Entity::registerEntity(SlapperZombie::class, true);
     Entity::registerEntity(SlapperSquid::class, true);
     Entity::registerEntity(SlapperCow::class, true);
     Entity::registerEntity(SlapperSpider::class, true);
     Entity::registerEntity(SlapperPig::class, true);
     Entity::registerEntity(SlapperMushroomCow::class, true);
     Entity::registerEntity(SlapperWolf::class, true);
     Entity::registerEntity(SlapperLavaSlime::class, true);
     Entity::registerEntity(SlapperSilverfish::class, true);
     Entity::registerEntity(SlapperSkeleton::class, true);
     Entity::registerEntity(SlapperSlime::class, true);
     Entity::registerEntity(SlapperChicken::class, true);
     Entity::registerEntity(SlapperEnderman::class, true);
     Entity::registerEntity(SlapperCaveSpider::class, true);
     $this->getLogger()->debug("Entities have been registered!");
     $this->getServer()->getPluginManager()->registerEvents($this, $this);
     $this->getLogger()->debug("Events have been registered!");
     $this->saveDefaultConfig();
     $this->getLogger()->debug("Config has been saved!!!");
     $this->getLogger()->info("Slapper is enabled! Time to slap!");
 }