public class UnionLevelUpgradeManager { private static Map<Integer, UnionLevelUpgrade> levelUpgrades;
static {
synchronized (UnionLevelUpgradeManager.class) {
if(levelUpgrades == null)
reloadLevelUpgrades();
}
}

public static synchronized  void reloadLevelUpgrades() {

if(levelUpgrades == null) 
levelUpgrades = new HashMap<Integer, UnionLevelUpgrade>();
        }
}