code: public static void setInstance(Cache cache) throws GuildWars2Exception {
  		if (instance != null)
  			throw new GuildWars2Exception(ErrorCode.Other, "Instance already initialized");
  		instance = new GuildWars2(cache);
  	}
docs: Use this to initialize instance with custom cache
  
  @param cache {@link Cache}
  @throws GuildWars2Exception instance already exist