code: 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;
  	}
docs: Determine if a refresh ahead is needed.
  The default implementation checks if accessTime falls into the 3rd quarter of (expirationTime - createdTime)
  @param accessTime		last access time
  @param createdTime		created time
  @param expirationTime	end of TTL/TTI time
  @return	true if a refresh is needed, false otherwise