public long getVersionForMember(T mbr) {
    RegionVersionHolder<T> holder = memberToVersion.get(mbr);
    if (holder == null) {
      if (mbr.equals(myId)) {
        return getCurrentVersion();
      } else {
        return 0;
      }
    } else {
      return holder.getVersion();
    }
  }
get the last recorded region version number for the given member
geode-core/src/main/java/org/apache/geode/internal/cache/versions/RegionVersionVector.java