Add list element

[simonbyford]

What does this change?

Adds a new element type List which will be used to provide more structure around existing formats such as Key Takeaways.

This block element is novel in that it also contains block element, creating a recursive data structure. It is not currently anticipated that a List element will contain List elements, although there is no easy way to prevent this in the thrift definition.

The recursion did cause problems with Fezziwig's auto serialisation, which we have worked around by explicitly caching the serialisers for BlockElement. It is possible that we will change our approach here following work on Fezziwig itself by Emily Bourke.

How to test

Run tests, they should pass.

publishLocal and try building/testing content-api-scala-client and content-api with this library.

• concierge
• content-api-scala-client

[simonbyford]

Looks good to me. Will need approval from someone else in the team!

[davidfurey]

This change has been tested locally with data flowing from composer through to concierge

[emdash-ie]

Can you make a beta release without merging and test with that, as Justin suggests in chat?

[github-actions]

@davidfurey has published a preview version of this PR with release workflow run #49, based on commit 7c9ce77:

19.0.0-PREVIEW.add-list-element.2024-02-27T1153.7c9ce77e

Want to make another preview release?

Click 'Run workflow' in the GitHub UI, specifying the add-list-element branch, or use the GitHub CLI command:

gh workflow run release.yml --ref add-list-element

Want to make a full release after this PR is merged?

Click 'Run workflow' in the GitHub UI, leaving the branch as the default, or use the GitHub CLI command:

gh workflow run release.yml

[davidfurey]

This has been tested locally and now in CODE with the preview release

[davidfurey]

See also https://stackoverflow.com/questions/34399288/caching-implicit-resolution

(although implicit shadowing isn't a thing in Scala 3 - scala/scala3#5887)