code: public static AdvancedCache asyncWriteCache(
  			AdvancedCache cache,
  			Flag extraFlag) {
  		return cache.withFlags(
  				Flag.SKIP_CACHE_LOAD,
  				Flag.SKIP_REMOTE_LOOKUP,
  				Flag.FORCE_ASYNCHRONOUS,
  				extraFlag
  		);
  	}
docs: Transform a given cache into a cache that writes cache entries without
  waiting for them to complete, adding an extra flag.
  
  @param cache to be transformed
  @param extraFlag to add to the returned cache
  @return a cache that writes asynchronously