public long getContactTimestamp(MemberIdentifier memberIdentifier) {
      return ((TimeStamp) memberTimeStamps.get(memberIdentifier)).getTime();
    }
when a suspect is undergoing an availability check its identifier will
be in the membersInFinalCheck collection
geode-membership/src/integrationTest/java/org/apache/geode/distributed/internal/membership/gms/fd/GMSHealthMonitorJUnitTest.java