public static GrantorInfo getGrantor(DLockService service, int dlsSerialNumber,
      InternalDistributedSystem sys) {
    return basicOp(-1, service, dlsSerialNumber, sys, null, GET_OP);
  }
Asks the elder who the grantor is for the specified service. If no grantor exists then makes us
the grantor.

@param service the service we want to know the grantor of.
@param sys the distributed system
@return information describing the current grantor of this service and if it needs recovery.
geode-core/src/main/java/org/apache/geode/distributed/internal/locks/GrantorRequestProcessor.java