Code

package me.T0X1C.picksell;

import me.mrCookieSlime.QuickSell.Shop;

import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.block.Action;
import org.bukkit.event.player.PlayerInteractEvent;
import org.bukkit.inventory.ItemStack;
import org.bukkit.plugin.java.JavaPlugin;

public class Main extends JavaPlugin implements Listener {

	public void onEnable() {
		getServer().getPluginManager().registerEvents(this, this);
		getServer().getLogger().info("§3§lOP §b§lPrison §8- §7Picksell Enabled!");
	}

	public void onDisable() {

	}

	@EventHandler
	public void PlayerInteract(PlayerInteractEvent e) {
		Player player = e.getPlayer();
		Shop shop = Shop.getHighestShop(player);
		ItemStack pick = new ItemStack(Material.DIAMOND_PICKAXE);
		if(shop == null) {
			player.sendMessage("§cShop not found!");
			return;
		} else if(e.getAction() == Action.RIGHT_CLICK_AIR && ((e.getAction() == Action.RIGHT_CLICK_BLOCK) && (e.getPlayer().getItemInHand() == pick))) {
			shop.sellall(player, "");
		}
	}
}