WIP Minimal maven->gradle evaluation

[jimschubert]

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\.
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Description of the PR

Evaluating what it would take to convert from maven to gradle. See #200

[jmini]

What about openapi-generator-maven-plugin ? I have the feeling that your current conversion is not creating a valid maven plugin out of the source code.

We need to apply a gradle plugin to replace the fact that the maven project is a <packaging>maven-plugin</packaging>. Something like https://plugins.gradle.org/plugin/com.liferay.maven.plugin.builder (or an other one, I just did a quick google search).

[jimschubert]

@jmini thanks for doing a search for that.

I expect this PR to take some time (a week or more). It will not only need to update maven -> gradle build scripts, but also CI scripts, hard-coded build outputs in all samples scripts (around 400 scripts, mostly search/replace but need to be visually checked), Docker scripts, etc. Looking at our CI scripts, I see some areas for various improvements which I'll probably do as a part of this PR.

Do you think it would be helpful if I create a TODO list for tracking items as I find them, and as I finish them up? This way we can track my progress.

[jmini]

I am really glad you start this. I imagine this will be a lot of work.

Maybe you can put your TODO list directly in the issue #200. This way I can see if I have additional ideas.

I also would like to test from time to time. I will wait until you tell that there is something that is ready to be tested locally.

[jimschubert]

This is on hold, pending investigation/research on issues with deploying from Travis CI to Sonatype via gradle.

[jimschubert]

Travis deploys have cleaned up. But I'm closing this since I'd basically need to redo it at this point.