[Java][MicroProfile] Support additionalProperties with Jackson

[joschi]

When additionalProperties is set to true, use an additionalProperties attribute and @JsonAnySetter and @JsonAnyGetter annotations instead of extending HashMap.

Refs #20853
Refs #20947

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[wing328]

thanks for the PR

do you mind filing a new one based on the latest master?

I think your change was based on master when we were stuck with v7.14.0 release since last Thur.

now the master refers to v7.15.0-SNAPSHOT version

[joschi]

do you mind filing a new one based on the latest master?

Done. 😃

[wing328]

what about adding this to the github workflow so that it will be tested moving forward?

https://github.com/OpenAPITools/openapi-generator/blob/master/.github/workflows/samples-java-client-jdk11.yaml

[wing328]

can we revert these change in the templates to keep the indentation?

[wing328]

thanks for the pr

let's give it a try

[xSAVIKx]

Hey @wing328, @joschi, isn't this a breaking change? Sometimes it was very desirable to have open-ended hashmap as a super interface for a set of objects.
With the current change one will have to hand-craft a map from the objects.

E.g. we were using it for "config" objects where some of the configurations are known and required (so we want to explicitly document them in the schema), but others' may come in a free-form format.
So now if we migrate to the new generator versions we'll end up with a broken system with no way to easily overcome the change.
Should there be at least an auto-generated method, smth like toMap() to have backward-compatible behavior?