docs: protected boolean refreshAheadNeeded(long accessTime, long createdTime, long expirationTime){
  		long ttl4 = (expirationTime - createdTime) / 4;
  		if (ttl4 < 0){
  			ttl4 = 0;
  		}
  		
  		long start = createdTime + ttl4 * 2;
  		long end = expirationTime - ttl4;
  		
  		return accessTime > start && accessTime < end;
  	}