public static void addSurpriseMember(DistributedSystem sys, DistributedMember mbr,
      long birthTime) {
    getDistribution(sys).addSurpriseMemberForTesting((InternalDistributedMember) mbr, birthTime);
  }
add a member id to the surprise members set, with the given millisecond clock birth time
geode-dunit/src/main/java/org/apache/geode/distributed/internal/membership/api/MembershipManagerHelper.java