[dart] json_serializable: remove experimental generator

[agilob]

I added this generator to help out with future migrations, but it doesn't look like anyone is using it, contributing to it or even reporting bugs. It adds extra maintenance burden to dart generators, so it can go away.

It was always marked as experimental.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  For Windows users, please run the script in Git BASH.
• File the PR against the correct branch: master (5.3.0), 6.0.x
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

[agilob]

@jaumard @josh-burton @amondnet @sbu-WBT @kuhnroyal @ahmednfwela @wing328

[ahmednfwela]

is this replaceable by dart-dio-next?

[agilob]

is this replaceable by dart-dio-next?

No, this is a breaking change, it's up to users to decide which other generator to use. dart-dio-next support null-safety, this one doesn't and won't.

[ahmednfwela]

are there extra features that this supports better than dart-dio-next? or is it just different libraries?

if it's just different libraries, then I think it is ok to remove, since dart-dio-next is built to be library agnostic.

if it has better features, then we can migrate them to dart-dio-next first before it's removed.

[agilob]

or is it just different libraries?

It's a different serialization library that generates code using compile time. I added it as I was big user of json_serializable, but since they (j_s) IMO made quite poor design choices while upgrading package to dart 2.12 I stopped using that library, no one else contributed to this generator and no bug was raised, which simply means it's not used.

[agilob]

Updated branch just to trigger failing test (failed to download mvn dependencies)

[kuhnroyal]

I am fine with this, we can always add it back again later after the NNBD migration.

[agilob]

Can we get this in @wing328 pls? Failure is unrelated

[agilob]

Thanks :)