AVRO-3676: Produce valid toString() for UUID JSON

[andeb]

What is the purpose of the change

In addition to #1204, this pull request wraps UUIDs in quotes to produce a valid JSON.

Verifying this change

Added test that validates UUID toString() behaviour

Documentation

• Does this pull request introduce a new feature? no

[RyanSkraba]

This LGTM -- keeping in mind (as always), parsing a data representation from .toString() is probably never really what the user wants, especially if they expect Avro-flavoured JSON encoding.

In this case, the right thing to do would be to use .toString() for debugging and a human-readable representation, and JsonEncoder to generate strict Avro JSON.

[RyanSkraba]

Cherry-picked to branch-1.11.

I also created a JIRA to track this change: AVRO-3676 -- The ASF JIRA unfortunately needed to disable public signups -- would you like us to create an account for you for contributor credit?

[andeb]

Thank you @RyanSkraba. It would be great if you could create an account for me on JIRA.

Noted regarding data representation using .toString(). I use it as a trick for tests only where I assert some big Avro JSONs to the expected JSON in some tests.

Originally I was using JsonEncoder to generate the Avro JSON, however it was a bit tricky to assert fields with logicalType decimal and timestamp as they get encoded as byte and long and it is not immediately clear the conversion when reading the test.