DOCS-15368 - Clarify UUID changes

[mongoKart]

Pull Request Info

PR Reviewing Guidelines

JIRA - https://jira.mongodb.org/browse/DOCS-15368
Staging - https://docs-mongodbcom-staging.corp.mongodb.com/java/docsworker-xlarge/docs-15368-clarify-uuid/upgrade/

Self-Review Checklist

• Is this free of any warnings or errors in the RST?
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[ccho-mongodb]

LGTM, a couple suggestions to make the implications of the change more clear.

[ccho-mongodb]

Suggestion:
Link to the API documentation of UuidRepresentation enum since it may not be clear what the various LEGACY UUID representations are. For example, here's the API docs for v4.0 of the driver:

http://mongodb.github.io/mongo-java-driver/4.0/apidocs/bson/org/bson/UuidRepresentation.html

Alternatively, if the intention is to present a concrete example, use the JAVA_LEGACY representation as the example.

[ccho-mongodb]

Suggestion:
While I read that it "strictly controls how the driver decodes UUIDs", and it may currently be implied, I think is important to explicitly call out that the prior version disregarded the setting. Perhaps something like:

"Previous versions disregarded the value of this setting setting when decoding UUIDs."

Also, I think it could be helpful to mention what would happen if they had been using the wrong encoding. Does it throw an exception and if so, what type? Users searching for the symptom could identify the issue more easily and correct the problem.

[mongoKart]

My testing may have been incomplete, but I wasn't able to get an exception thrown. Leaving as is for now.