code: public static void setInstance(Application application) {
  		if (application == Application.instance) {
  			return;
  		}
  		if (Application.instance != null) {
  			throw new IllegalStateException("Application cannot be changed");
  		}		
  		if (application == null) {
  			throw new IllegalArgumentException("Application cannot be null");
  		}
  		Application.instance = application;
  	}
docs: Sets the application of this vm. Can only be called once (except a second
  time with the same application). This method should only be called by a
  frontend or a backend main class.
  
  @param application normally the created by createApplication method