Add support for parsing java.util.Date

[GnaneshKunal]

We create and register a new class to parse java.util.Date objects.

[asherkin]

Hi there! Thanks for putting this PR together!

The design intention here was to only be a low-level building block and not to expose high-level implementations for the standard Java objects. This is why e.g. List is only contained inside a test definition.

Did you run into an issue with Date where it couldn't be parsed with the already exposed API?

Unfortunately I don't think I can take this as-is due to the breaking API changes for library consumers (who provide their own types to be parsed).

[GnaneshKunal]

@asherkin

Understood. Based on your suggestion, I have reworked my changes in the other repository.

I'm closing this Pull Request. Also, what do you suggest for External types? I see we are throwing an Error while parsing such data formats.

[asherkin]

Also, what do you suggest for External types? I see we are throwing an Error while parsing such data formats.

Looks like the underlying data is largely the same, just none of the automatic behaviour - it looks relatively straightforward to add, but a per-object implementation must be provided in all cases.

Could you open an issue with an example of a real-world Externalizable implementation and its corresponding serialised output?