In version 3.6 struct Ice.Optional is not backward compatible with previous versions
In version 3.6 the structure Ice.Optional marked attribute [Serializable] and implemented interface ISerializable. Because defined method GetObjectData, now serialization occurs by different rules, not because it was in the previous version - default on public properties. This is nowhere mentioned in the documentation, there is no mention of it in the list of changes in the new version. Perhaps such similar changes also affected other parts of the code. It would be nice if the documentation listed these important changes.