code: private long calExpirationTime(long operatorTime, long relativeSize) {
  		if (operatorTime < Long.MAX_VALUE) {
  			return operatorTime - relativeSize - allowedLateness - 1;
  		} else {
  			// When operatorTime = Long.MaxValue, it means the stream has reached the end.
  			return Long.MAX_VALUE;
  		}
  	}
docs: Calculate the expiration time with the given operator time and relative window size.
  
  @param operatorTime the operator time
  @param relativeSize the relative window size
  @return the expiration time for cached rows