Fix startup issue on 1.16 servers

Fixes #829

pom.xml

@@ -18,7 +18,7 @@
 		<dependency>
 			<groupId>org.spigotmc</groupId>
 			<artifactId>spigot-api</artifactId>
-			<version>1.15.2-R0.1-SNAPSHOT</version>
+			<version>1.16.1-R0.1-SNAPSHOT</version>
 			<scope>provided</scope>
 		</dependency>
 		<!-- Boss -->

src/main/java/com/gamingmesh/jobs/nmsUtil/v1_16.java

@@ -0,0 +1,59 @@
+package com.gamingmesh.jobs.nmsUtil;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.bukkit.OfflinePlayer;
+import org.bukkit.attribute.Attribute;
+import org.bukkit.block.Block;
+import org.bukkit.entity.Entity;
+import org.bukkit.entity.LivingEntity;
+import org.bukkit.entity.Player;
+import org.bukkit.event.block.BlockPistonRetractEvent;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.meta.Damageable;
+import org.bukkit.inventory.meta.SkullMeta;
+
+import com.gamingmesh.jobs.NMS;
+
+public class v1_16 implements NMS {
+
+    @Override
+    public List<Block> getPistonRetractBlocks(BlockPistonRetractEvent event) {
+	List<Block> blocks = new ArrayList<>();
+	blocks.addAll(event.getBlocks());
+	return blocks;
+    }
+
+    @Override
+    public String getRealType(Entity entity) {
+	return entity.getType().name();
+    }
+
+    @Override
+    public ItemStack getItemInMainHand(Player player) {
+	return player.getInventory().getItemInMainHand();
+    }
+
+    @Override
+    public void setItemInMainHand(Player player, ItemStack item) {
+	player.getInventory().setItemInMainHand(item);
+    }
+
+    @Override
+    public double getMaxHealth(LivingEntity entity) {
+	return entity.getAttribute(Attribute.GENERIC_MAX_HEALTH).getBaseValue();
+    }
+
+    @Override
+    public short getDurability(ItemStack item) {
+	return (short) ((Damageable) item.getItemMeta()).getDamage();
+    }
+
+    @Override
+    public void setSkullOwner(SkullMeta meta, OfflinePlayer player) {
+	if (meta != null && player != null) {
+	    meta.setOwningPlayer(player);
+	}
+    }
+}