Example plugin (PR for CloudburstMC/Nukkit#1028)

plugin.yml

name: SkellyMovePlugin
main: sample.SkellyMovePlugin
version: "1.0.0"
api: ["1.0.9"]

sample\SkellyMovePlugin.java

package sample;

import cn.nukkit.block.Block;
import cn.nukkit.entity.Entity;
import cn.nukkit.entity.mob.EntitySkeleton;
import cn.nukkit.event.EventHandler;
import cn.nukkit.event.Listener;
import cn.nukkit.event.player.PlayerInteractEntityEvent;
import cn.nukkit.event.player.PlayerInteractEvent;
import cn.nukkit.item.Item;
import cn.nukkit.level.Level;
import cn.nukkit.level.Sound;
import cn.nukkit.math.BlockFace;
import cn.nukkit.nbt.tag.CompoundTag;
import cn.nukkit.nbt.tag.DoubleTag;
import cn.nukkit.nbt.tag.ListTag;
import cn.nukkit.plugin.PluginBase;
import cn.nukkit.utils.TextFormat;

public class SkellyMovePlugin extends PluginBase implements Listener {
    
    @EventHandler
    public void onInteractEntity(PlayerInteractEntityEvent event) {
        Entity entity = event.getEntity();
        if (entity instanceof EntitySkeleton) {
            entity.saveNBT();
            Item playerItem = event.getItem().clone();
            playerItem.setCount(playerItem.getCount() -1);
            event.getPlayer().getInventory().setItemInHand(playerItem);
            Item drop = Item.get(Item.BONE);
            drop.setCompoundTag(new CompoundTag("").putCompound("SkellyData", entity.namedTag.copy()));
            drop.setCustomName(TextFormat.YELLOW+"Captured Skeleton");
            Level level = entity.getLevel();
            entity.close();
            level.dropItem(entity, drop, null, true, 20);
            level.addSound(entity, Sound.MOB_GHAST_FIREBALL);
            event.setCancelled();
        }
    }
    
    @EventHandler
    public void onInteract(PlayerInteractEvent event) {
        Item item = event.getItem();
        Block block = event.getBlock();
        if (item.hasCompoundTag() && item.getId() == Item.BONE && item.getNamedTag().contains("SkellyData") && block.getId() != 0) {
            CompoundTag entityData = item.getNamedTag().getCompound("SkellyData");
            if (!entityData.isEmpty()) {
                BlockFace face = event.getFace();
                Item playerItem = event.getItem().clone();
                playerItem.setCount(playerItem.getCount() -1);
                event.getPlayer().getInventory().setItemInHand(playerItem);
                Entity entity = Entity.createEntity("Skeleton", block.getChunk(),
                        entityData.putList(new ListTag<>("Pos")
                                .add(new DoubleTag("", block.x + face.getXOffset() * 0.2 + face.getZOffset() * 0.5 + 0.25))
                                .add(new DoubleTag("", block.y + face.getYOffset()))
                                .add(new DoubleTag("", block.z + face.getZOffset() * 0.2 + face.getXOffset() * 0.5 + 0.25))
                        )
                );
                entity.spawnToAll();
                block.getLevel().addSound(entity, Sound.BLOCK_BEEHIVE_EXIT);
                event.setCancelled();
            }
        }
    }
    
    @Override
    public void onEnable() {
        getServer().getPluginManager().registerEvents(this, this);
    }
}