Dart dio update (!13213) · Merge requests · OpenAPI Tools / openapi-generator

Created by: warrenisarobot

Referenced issue:

This PR addresses issues with the dart-dio generator that arise from the Plaid OpenAPI spec, found at:

Added Date types as primitives
Updated model/class template to handle null enum values in documentation comments
Updated jmoustache version to 1.15 to handle null checks in list values. Reference here: https://github.com/samskivert/jmustache/issues/96
Added update as a keyword

[X ] 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 (6.1.0) (minor release - breaking changes with fallbacks), 7.0.x (breaking changes without fallbacks)
If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.