public static VersionTag create(VersionSource memberId) {
    VersionTag tag;
    if (memberId instanceof DiskStoreID) {
      tag = new DiskVersionTag();
    } else {
      tag = new VMVersionTag();
    }

    tag.setMemberID(memberId);

    return tag;
  }
Creates a version tag of the appropriate type, based on the member id
geode-core/src/main/java/org/apache/geode/internal/cache/versions/VersionTag.java