Add JVM-based JSON formatter

[jamietanna]

Add JVM-based JSON formatter

Currenly, if consumers of Spotless want to format their JSON files, they
need to do this by adding prettier, which increases the dependencies a
project needs.

To simplify things for consumers, as documented in #850, we can provide
a JVM-based JSON formatter, using org.json's JSON formatting.

To follow how we've done this with other formatters, we can retrieve
org.json's JAR at runtime, and retrieve the classes via Reflection,
instead of adding this as a lib-extra project, with an explicit
dependency.

To validate this fully, we want a few straightforward JSON files to
validate before/after, but we can also use a sample Cucumber JSON
report as a much more complex example of what happens, which we've
removed any data objects from its source, so the files are smaller.

We also want our consumers to be able to configure the indentation size.

Closes #850.

---

Raising this as an early draft PR for feedback if possible!

I've also tested this against a project of mine that has a lot of JSON files, and it works nicely 😄

---

TODOs:

• Class name ends in Step, SomeNewStep.
• Class has a public static method named create that returns a FormatterStep.
• Has a test class named SomeNewStepTest.
• Test class has test methods to verify behavior.
• Test class has a test method equality() which tests equality using StepEqualityTester (see existing methods for examples).
• PR allows edits from maintainers
• Git history
• Gradle integration
• CHANGES.md
• After creating the PR, please add a commit that adds a bullet-point under the -SNAPSHOT section of CHANGES.md, plugin-gradle/CHANGES.md, and plugin-maven/CHANGES.md which includes:
  • a summary of the change
  • either
    • a link to the issue you are resolving (for small changes)
    • a link to the PR you just created (for big changes likely to have discussion)

[nedtwigg]

Thanks, this is pretty close to mergeable.

[jamietanna]

Thanks, that's super helpful! Would we say tabs are a requirement for JSON btw? I know they're offered for other means, but I can't think of any time I've seen them as JSON is usually space pretty-printed 🤔

[nedtwigg]

Tabs are definitely not a requirement to merge, I just want to make it easy for some someone else to add them later if they want.

[jamietanna]

Looks like it's still not happy, I'm seeing:

* What went wrong:
Could not determine the dependencies of task ':spotlessApply'.
> Could not create task ':spotlessJsonApply'.
   > Could not create task ':spotlessJson'.
      > Cannot invoke method simple() on null object

And given it's pretty close to what is used in i.e. KotlinExtension I'm not sure where to go from here 😓

[jamietanna]

Hey @nedtwigg was wondering if you or any of the team could spot why this doesn't seem to be working?

[nedtwigg]

At least right now, the tests are failing because the PR needs a spotlessApply. https://app.circleci.com/pipelines/github/diffplug/spotless/1060/workflows/c9ee7f59-a168-4836-8f02-88809ebc3730/jobs/5994

Because of that I can't see a test failure stacktrace in CI. Seems unlikely but possible that json is some kind of keyword or special operator, maybe try json2 just to test? If that is the problem it might be best for the example code to just be format 'json', com.diffplug.spotless.JsonExtension.class { (I got the package wrong here, but you get the idea).

This is a useful feature, but I throttle my time on Spotless. I won't pull this locally and dig around, and I don't trust stacktraces that I can't verify for myself in our CI setup. I can be more helpful if you can reproduce whatever you are seeing locally in the public CI.

[jamietanna]

Thanks Ned - I appreciate the help! I've added some extra test cases to show the various bits I've tried, which shows a bit more what I've been seeing.

Let me know if you'd like --stacktrace --info added for more logging detail.

[nedtwigg]

Very close! Just some docs changes.

[jamietanna]

Thanks Ned - good points for those documentation tweaks 👍

[nedtwigg]

Published in plugin-gradle 5.14.0.

[elakkss]

Hi, Is this available in plugin-maven as well?.

[jamietanna]

I don't see it there (yet) - I don't use Maven so didn't contribute it, but I can see about getting a PR raised at some point in the next few weeks, or if you'd like to pick it up, feel free :)

[talios]

Any one know if this (along with #910) will be merged/released soon?

[jamietanna]

Hey talios, do you mean the Gradle or Maven plugin? Gradle been live for a while, the Maven and YAML changes won't be done at least by me any time soon sorry

[talios]

@jamietanna Ahh I was meaning the maven plugin - if it's just a matter of wiring things up from library->mojo I could probably take a look at that ca814b4 commit and see what's up.