reject non-canonical UUID strings in UUIDConverter

[rootvector2]

UUID.fromString accepts abbreviated groups like 1-1-1-1-1 and silently canonicalizes them to 00000001-0001-0001-0001-000000000001, so UUIDConverter converts strings that are not the canonical 8-4-4-4-12 form; found while auditing the converters that delegate straight to a lenient JDK parse, and fixed by rejecting any input that does not round-trip to its canonical string (upper case still converts).

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[garydgregory]

Hello @rootvector2
-1 unless you can convince us otherwise. This class reflects what Java's own UUID class provides through java.util.UUID.fromString(String).
It seems to me that this PR would narrow what the JRE provides out of the box.

One could argue that java.util.UUID.fromString(String) is lenient by accepting input with leading '0's in its compoenents but that's not something we can change.

Where did you get the requirement that the String form of a UUID or a Converter output in general must roundtrip with its String inout? Maybe I missed it.

I've updated the Javadoc which might give readers better expectations.

[rootvector2]

Fair enough. I was treating a canonical round-trip as an implicit expectation, but you're right that there's no spec backing it and the converter should mirror UUID.fromString rather than narrow what the JRE accepts. The leading-0 leniency is the JDK's call, not ours. Withdrawing this one, and thanks for the Javadoc clarification.

[rootvector2]

Closing per the discussion above.