fix: #1466 additionalProperties works now in spring generator

[benfonty]

When additional properties is true, use an additionalProperties attribute and @JsonAnySetter and @JsonAnyGetter instead of inherit from Map. I followed what was done for java.jersey2 in #6518.

This fixes #1466 only for spring target.

cc @nmuesch

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[bfrggit]

Q1: What if additionalProperties is not boolean, (i.e., the additional properties have a certain type of values)? Does this also work?
Q2: Can this be done for the Java generator too?

[benfonty]

Q1: What if additionalProperties is not boolean, (i.e., the additional properties have a certain type of values)? Does this also work?

Yes, if the type is string for example, additionalAttributes has type Map<String, String> instead of Map<String, Object>.

Q2: Can this be done for the Java generator too?

This can be done for all java generators, but the code might differ from generator to generator, as the template are not always the same. quote https://github.com/OpenAPITools/openapi-generator/pull/6518/files#diff-e939f76e33b14e4de9645853ba5bdeb050b5fa0b6676693ff900fd60aaf08528R375

[jameswynn]

The failed bitrise test looks like an intermittent failure. Is that all that is blocking this PR?

[benfonty]

The failed bitrise test looks like an intermittent failure. Is that all that is blocking this PR?

I don't know. There were two failed builds with the same error that seems indeed intermittent. I am not sure what to do to fix it.

[jameswynn]

@cbornet The normal build passes, but bitrise chokes. Any advice?