code: public static Zxid fromProtoZxid(ZabMessage.Zxid zxid) {
      return new Zxid(zxid.getEpoch(), zxid.getXid());
    }
docs: Converts protobuf Zxid object to Zxid object.
  
  @param zxid the protobuf Zxid object.
  @return the Zxid object.