public synchronized <Data> void append(Data value, KeyDescriptor<Data> descriptor) throws IOException {
    final BufferExposingByteArrayOutputStream bos = new BufferExposingByteArrayOutputStream();
    DataOutput out = new DataOutputStream(bos);
    descriptor.save(out, value);
    final int size = bos.size();
    final byte[] buffer = bos.getInternalBuffer();
    append(buffer, size);
  }
public synchronized <Data> void append(Data value, KeyDescriptor<Data> descriptor)