[java] No @NotNull annotation for readOnly (required) attributes

[daniel-sc]

fixes #5026

This duplicates #5960 (which was stale because of missing feedback/updates from creator).

@bbdouglas @sreeshas @jfiala @lukoyanov @cbornet @jeff9finger @karismann @Zomzog @lwlee2608 @nmuesch

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[daniel-sc]

Hi @bbdouglas @sreeshas @jfiala @lukoyanov @cbornet @jeff9finger @karismann @Zomzog @lwlee2608 @nmuesch
Could anyone please review this?
I'm happy to update the PR if some things don't match expectations.

[feech]

138 files have changed! and mostly of them just formatting.
I am not a reviewer but you made everything to slow down the process.

[daniel-sc]

@feech this is because of the required re-generation of docs (./bin/utils/export_docs_generators.sh) - together with the (known) issue that newline can not be controlled well with mustache..

(if you ask me, this shows why the general best practice is not to version control generated content - but of course others might have more insights for this specific repository!)

[daniel-sc]

Hi @bbdouglas @sreeshas @jfiala @lukoyanov @cbornet @jeff9finger @karismann @Zomzog @lwlee2608 @nmuesch
Anyone up for a review and/or feedback?
I'd be happy to resolve the merge conflicts that appeared in the meantime, but only if there is some reasonable expectation on this getting merged ;-)

[wing328]

@daniel-sc thanks for the PR. Can you please resolve the merge conflicts and PM me via Slack?

https://join.slack.com/t/openapi-generator/shared_invite/zt-12jxxd7p2-XUeQM~4pzsU9x~eGLQqX2g