Indicates whether OSPF should perform an unplanned hitless
restart using grace LSAs. Note that etsysOspfExtDoGraceHitless
has a higher priority than this object. Therefore if both
etsysOspfExtDoGraceHitless and this object are both set to
'true' on activation, OSPF will assume it is undergoing a
planned hitless restart. If only this object is 'true', then
OSPF will attempt an unplanned hitless restart, and send out
grace LSAs on activation.