[Cases] Fix fields query parameter in the _find API

[cnasikas]

Summary

If you pass a single value in the fields query parameter you get a bad request error. This is happening because io-ts expects an array of strings but if a single value is provided is being provided as a single string. This PR fixes this issue.

Checklist

Delete any items that are not applicable to this PR.

• Unit or functional tests were updated or added to match the most common scenarios

For maintainers

• This was checked for breaking API changes and was labeled appropriately

Release notes

Fix bug when providing a single value to the fields query parameter of the Cases find API.

[elasticmachine]

Pinging @elastic/response-ops (Team:ResponseOps)

[elasticmachine]

Pinging @elastic/response-ops-cases (Feature:Cases)

[cnasikas]

@elasticmachine merge upstream

[peteharverson]

Tested and LGTM

[lcawl]

@elasticmachine merge upstream

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: a9c7d54
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Metrics [docs]

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
cases	85.1KB	85.1KB	+20.0B

History

• 💛 Build #32495 was flaky 751fd57
• 💔 Build #32190 failed c071f69
• 💔 Build #32145 failed a7f2e13
• 💔 Build #32134 failed c8378c1

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @cnasikas

[academo]

nice. Thanks for adding that extra test.

[kibanamachine]

💔 All backports failed

Status	Branch	Result
❌	7.17	Backport failed because of merge conflicts
❌	8.1	Backport failed because of merge conflicts

Manual backport

To create the backport manually run:

node scripts/backport --pr 128143

Questions ?

Please refer to the Backport tool documentation

[cnasikas]

I decided to not backport to the previous versions as it is risky and the bug fix is of low importance.