@Override
public void write(DataOutput out) throws IOException {
// Serialize class names of each non-null field
final ClassIndex index = new ClassIndex();
if (fst != null) index.addClass(fst.getClass());
if (snd != null) index.addClass(snd.getClass());
index.write(out);
// Indicate which fields are null
out.writeByte((fst == null ? FST_NULL : NOT_NULL) | (snd == null ? SND_NULL : NOT_NULL));
// Serialize each non-null field
if (fst != null) {
out.writeByte(index.getId(fst.getClass()));
fst.write(out);
}
if (snd != null) {
out.writeByte(index.getId(snd.getClass()));
snd.write(out);
}
}
@Override
public void write(DataOutput dataOutput) throws IOException {
first.write(dataOutput);
second.write(dataOutput);
}