Main.java

	private static final Field VEHICLE;
	private static final Field PASSENGERS;
	
	static {
		Field vehicle = null, passengers = null;
		for (Field field : PacketPlayOutMount.class.getDeclaredFields()) {
			if (field.getType() == int.class) {
				field.setAccessible(true);
				vehicle = field;
			} else if (field.getType() == int[].class) {
				field.setAccessible(true);
				passengers = field;
			}
		}
		VEHICLE = vehicle;
		PASSENGERS = passengers;
	}
	
	public static Packet getMountPacket(int vehicle, int... passengers) {
		try {
			PacketPlayOutMount packet = new PacketPlayOutMount();
			VEHICLE.set(packet, vehicle);
			PASSENGERS.set(packet, passengers);
			return packet;
		} catch (IllegalAccessException e) {
			throw new RuntimeException(e);
		}
	}
	
	public static List<Packet> setNameTag(Entity entity, String... lines) {
		net.minecraft.server.v1_12_R1.World world = ((CraftWorld) entity.getWorld()).getHandle();
		int[] passengers = new int[lines.length];
		List<Packet> packets = new LinkedList<>();
		
		for (int i = 0; i < lines.length; i++) {
			int size = (i - 1) * -1;
			EntitySlime holder = new EntitySlime(world);
			holder.setInvulnerable(true);
			Location location = entity.getLocation();
			holder.setPosition(location.getX(), location.getY(), location.getZ());
			holder.setInvisible(true);
			holder.setSize(size, false);
			
			EntityArmorStand line = new EntityArmorStand(world);
			line.setInvulnerable(true);
			line.setPosition(location.getX(), location.getY(), location.getZ());
			
			line.setInvisible(true);
			line.setSmall(true);
			line.setCustomName(lines[i]);
			line.setCustomNameVisible(true);
			
			passengers[i] = holder.getId();
			
			packets.add(new PacketPlayOutSpawnEntityLiving(holder));
			packets.add(new PacketPlayOutSpawnEntityLiving(line));
			packets.add(getMountPacket(holder.getId(), line.getId()));
		}
		
		packets.add(getMountPacket(entity.getEntityId(), passengers));
		
		return packets;
	}