Dart codegen bug fixes: honor prefix/suffix, handle operation return types, replaces Object with Map

[jeffmikels]

This pull requests modifies the Dart codegen and templates to accomplish the following:

• Dart codegen now respects the modelNamePrefix, modelNameSuffix, apiNamePrefix, and apiNameSuffix settings
• Dart codegen now properly handles the case when a query parameter is named _ (internally using the variable name q)
• Dart codegen now supports an additional property named apiClientName to override the default ApiClient
• CodegenOperation.java was modified to expose a returnInnerType field for those operations whose return value is an array or mapping type value.
• Dart codegen makes use of the new returnInnerType value to properly handle the return type of operations.
• Dart codegen now uses Map as the default type for an otherwise unspecified api object.

@jaumard (2018/09) @josh-burton (2019/12) @amondnet (2019/12) @sbu-WBT (2020/12) @kuhnroyal (2020/12) @agilob (2020/12) @ahmednfwela (2021/08)

PR checklist

• [x] Read the contribution guidelines.
• [x] 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.
• [x] 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.
• [x] File the PR against the correct branch: master (6.0.1) (patch release), 6.1.x (breaking changes with fallbacks), 7.0.x (breaking changes without fallbacks)
• [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.

[jeffmikels]

Are there any other questions?

[wing328]

@jeffmikels thanks for the PR.

I would suggest breaking down the PR into smaller one for easier review and merge.

What about filing a separate for the following change to start with?

• Dart codegen now respects the modelNamePrefix, modelNameSuffix, apiNamePrefix, and apiNameSuffix settings

[jeffmikels]

@jeffmikels thanks for the PR.

I would suggest breaking down the PR into smaller one for easier review and merge.

What about filing a separate for the following change to start with?

• Dart codegen now respects the modelNamePrefix, modelNameSuffix, apiNamePrefix, and apiNameSuffix settings

The code changes were extensive because they required a number of changes to be implemented simultaneously. The respecting of modelNamePrefix, modelNameSuffix, apiNamePrefix, and apiNameSuffix settings was a nearly trivial change. The other changes were more important and the main reason for the PR.

[kuhnroyal]

@jeffmikels Do you have plans to break this in smaller pieces? Otherwise please be so kind and close the PR.

[Nexushunter]

Is there an ETA on this? I'm running into the issue of the Object.listFromJson here. If needed I can pick up the object => map conversion.