void write(OutputStream out) throws IOException{
    DataOutput dataOut = new DataOutputStream(out);
    dataOut.writeInt(FORMAT_VERSION_NUMBER);

    DataInputOutputUtilRt.writeSeq(dataOut, myDataMap.entrySet(), entry -> {
      IOUtil.writeUTF(dataOut, entry.getKey());
      DataInputOutputUtilRt.writeSeq(dataOut, entry.getValue(), data -> IOUtil.writeUTF(dataOut, data));
    });

    writeStringIntMap(dataOut, myContextMaxStamps);

    DataInputOutputUtilRt.writeSeq(dataOut, myValueStamps.entrySet(), entry -> {
      IOUtil.writeUTF(dataOut, entry.getKey());
      writeStringIntMap(dataOut, entry.getValue());
    });
  }
void write(OutputStream out)