[Java][Client] Add support for the new Spring RestClient

[Nicklas2751]

Created a new Java Client for the Spring 6 RestClient.
This solves #17571

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/configs/*.yaml
  ./bin/utils/export_docs_generators.sh
  

  (For Windows users, please run the script in Git BASH)
  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.
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  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
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[wing328]

the CI tests failed. can you please take a look when you've time?

[wing328]

can you please resolve the merge conflicts when you've time?

[Nicklas2751]

the CI tests failed. can you please take a look when you've time?

I had to regenerate the sample tests which were missing the @Ignore.
All other java clients I looked at had it disabled too. But for what are these test if their disabled and not runnable?

EDIT:
Found the answer: https://github.com/openapitools/openapi-generator/wiki/How-to-add-a-generator-for-a-new-language-or-framework :)

[Nicklas2751]

can you please resolve the merge conflicts when you've time?

sure

[Nicklas2751]

Hm, cause of the failing check I re-reun the whole generate-samples script and now I have changes in the go petstore sample 🤔

[wing328]

please ignore those for the time being

[wing328]

outdated samples already fixed in the master

[wing328]

@Nicklas2751 thanks for the PR, which has been merged into the master

[AhmedOsama1999]

There is an issue when generateClientAsBean is true the client classes are not annotated with @component like resttemplae library

[Nicklas2751]

@AhmedOsama1999 The documentation says the following for generateClientAsBean :

For resttemplate, configure whether to create ApiClient.java and Apis clients as bean (with @component annotation).

So, it's currently a resttemplate only feature.