Return null if no error has been detected, and a descriptive string otherwise. Checks rslt field to see if an error has been detected (subclasses should use setRsltIfNeeded to flag an error. Default implementation also makes sure that the lease expired close to the desired expiration, or that the lease's desired expiration has not been reached and the lease has not yet expired.
All source code are property of their respective owners. Java is a trademark of Sun Microsystems, Inc and owned by ORACLE Inc. Contact coftware#gmail.com.