// Initialize the event registry
EventRegistry.initialize();
// Create a class for listening for events,
// and register it by using the function below with an instance of that class.
EventRegistry.registry.register(eventListener);

@EventHandler
public void onPacketEvent(PacketEvent event) {
    Packet<?> packet = event.getPacket();
    if (packet instanceof PlayerMoveC2SPacket) {
        event.cancel();
    }
}