code: public static void setInstance(OkHttpClient client) throws GuildWars2Exception {
  		if (instance != null)
  			throw new GuildWars2Exception(ErrorCode.Other, "Instance already initialized");
  		instance = new GuildWars2(client);
  	}
docs: You need to call {@link #setInstance(Cache)} to create instance with custom
  caching<br/>
  This method will create instance with your custom Client
  @param client
  your custom client