YAML implementation with Jackson

[blacelle]

This follows #910.

It enables YAML formatting with Jackson

[nedtwigg]

Wow, you're on a roll! Needs

• no default includes
• add an entry to the giant table in the root README.md
  • be sure to run Spotless in Java 11 or less so that freshmark works
• take a look at the compileOnly thing, but no change is required

[blacelle]

This YAML integration comes with multiple limitations.

• Seemingly not management of YAML with multiple inner documents (May ba manageable, like Array vs Map in Gson)
• Removal of comments (yaml) Emit comments FasterXML/jackson-dataformats-text#36
• Invalid management of node reference YAML Anchors / References FasterXML/jackson-dataformats-text#98 Reopen: YAML Anchor, reference fails with simple example #123 FasterXML/jackson-dataformats-text#296
• More to come (as I'm no YML advanced user, I may be missing other YML feature being degraded)

@nedtwigg Would this remain acceptable, as long as these limitations are clearly documented?

[nedtwigg]

If this YAML formatter will be useful to you, then I want to merge it! If these limitations mean that it won't work for you, then I'd rather not merge it. I love to merge things that help people solve their own problems, and I'm skeptical of features that the PR author doesn't need, but just imagines other future users possibly needing.

The tests are all still failing. Hopefully we can fix them up and cut a release tomorrow :)

[blacelle]

Some notes for myself and other maven-preferred developper:

1. mvn tests can be run from the root with ./gradlew :plugin-maven:check --build-cache
2. It is unclear what cd plugin-maven && ../gradlew publishToMavenLocal will push in your local repository (cache issue?)
3. cd plugin-maven && ../gradlew test --tests '*yaml*' will trigger some tests, but it is unclear on which code they apply (cache issue?)
4. ./gradlew :plugin-maven:runMavenBuild :plugin-maven:test --tests '*yaml*' --no-build-cache seems to correctly discard the cached mvn plugin, and execute tests on the latest code.

[blacelle]

Wow. This was a burden, but now things are OK. These caches issues related to maven were a major difficulty.

We may invest in maven-harness:

	<dependency>
		<!-- https://maven.apache.org/plugin-testing/maven-plugin-testing-harness/getting-started/index.html -->
		<groupId>org.apache.maven.plugin-testing</groupId>
		<artifactId>maven-plugin-testing-harness</artifactId>
		<version>3.3.0</version>
		<scope>test</scope>
	</dependency>

in order not to execute tests through forked mvn commands (and deployment in a tmp repository. ). We may also imvest in unit-tests not plugin-based.

JSON integration was KO. I got caught by unexpected behavior of json-simple (which kind-of sortKeys by default, but in a different fashion than Gson when the option is on).

[nedtwigg]

Thanks for sticking with this! I think it's time for the maven build to get fixed up. Subscribe to #554, I'll have something to share there shortly.

[nedtwigg]

Published in plugin-maven 2.30.0.