http://www.bukkit.fr/index.php/topic/13447-probl%C3%A8me-de-config/

DoubleEnderchest.java

package fr.neatmonster.doubleenderchest;

import org.bukkit.entity.HumanEntity;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryCloseEvent;
import org.bukkit.event.inventory.InventoryOpenEvent;
import org.bukkit.event.inventory.InventoryType;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.ItemStack;
import org.bukkit.plugin.java.JavaPlugin;

import java.util.Arrays;

public class DoubleEnderchest extends JavaPlugin implements Listener {

    @Override
    public void onEnable() {
        getServer().getPluginManager().registerEvents(this, this);
    }

    @EventHandler
    public void onInventoryOpen(final InventoryOpenEvent event) {
        final HumanEntity player = event.getPlayer();
        final Inventory oldInv = event.getInventory();
        if (oldInv.getType() == InventoryType.ENDER_CHEST) {
            final Inventory newInv = getServer().createInventory(player, 54, InventoryType.ENDER_CHEST.getDefaultTitle());
            if (getConfig().isSet("enderchests." + player.getName()))
                newInv.setContents(getConfig().getList("enderchests." + player.getName()).toArray(new ItemStack[0]));
            else newInv.setContents(player.getEnderChest().getContents());
            player.openInventory(newInv);
            event.setCancelled(true);
        }
    }

    @EventHandler
    public void onInventoryClose(final InventoryCloseEvent event) {
        final Inventory inventory = event.getInventory();
        if (inventory.getSize() == 54 && inventory.getName().equals(InventoryType.ENDER_CHEST.getDefaultTitle())) {
            getConfig().set("enderchests." + event.getPlayer().getName(), Arrays.asList(inventory.getContents()));
            saveConfig();
        }
    }
}

plugin.yml

name: DoubleEnderchest
author: NeatMonster
version: 1.0
main: fr.neatmonster.doubleenderchest.DoubleEnderchest