9904 Fix double quoting default values in Kotlin Spring

[bamapookie]

Fix for #9904.

Kotlin files with default values that are not enums were getting double quoted (defaultValue = ""default"") in API file generation. This fixes the issue for query parameters.

The first commit adds a method to the petstore sample that uses the code path demonstrating this bug. See the second commit for the invalid source generated. (kotlin-springboot)

CC: Kotlin committee members @jimschubert, @dr4ke616, @karismann, @Zomzog, @andrewemery, @4brunu, and @yutaka0m

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Fix should go into 5.4.0 branch as well.

[bamapookie]

I'm unsure what to do here. There are tests failing for go and jaxrs, but I don't know why. I added a new endpoint to openapi-generator/src/test/resources/2_0/petstore.yaml, because that is the file that generated the samples, but the documentation in CONTRIBUTING.md says to update openapi-generator/src/test/resources/3_0/petstore-with-fake-endpoints-models-for-testing.yaml. Which one should I update?

[wing328]

For the Go related error in CircleCI node 2, please ignore that for the time being.

[bamapookie]

Rebased on current upstream master.

[wing328]

cc @jimschubert (2017/09) ❤️, @dr4ke616 (2018/08) @karismann (2019/03) @Zomzog (2019/04) @andrewemery (2019/10) @4brunu (2019/11) @yutaka0m (2020/03)

[wing328]

Tested locally to confirm the fix. Thanks for the PR.

I'll try to add some tests later to cover this.