[JAVA] fix several anyOf/oneOf problems

[martin-mfg]

Fix various problems when using anyOf or oneOf. Mostly focusing on the Jersey libraries.

I separated the fixed problems into different commits in this PR:

• commit 1: generate more child-specific methods where possible.
  e.g. in samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FakeAnyOfWIthSameErasureGet200Response.java we now also generate the method "getListInteger". Previously this was skipped due to "getListString" already being created.
  The mustache file changes also include a small simplification of the relevant template part. The Jersey anyOf*.mustache templates were a bit out of sync and needed to be aligned with their oneOf counterparts - see here for context.
• commit 2: When generating an anyOf/oneOf model with useBeanValidation=true, don't generate uncompilable code.
• commit 3: When generating a oneOf model which also is a map, don't generate uncompilable code.
• commit 4: Apply similar fixes to the Jersey anyOf*.mustache templates. As mentioned above, they were a bit out of sync.

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[wing328]

https://github.com/OpenAPITools/openapi-generator/actions/runs/11245644264/job/31266185926?pr=19817

please update the samples when you've time

overall the change looks good.

will merge after all tests pass

thank you

[martin-mfg]

@wing328 done :)

[wing328]

looks good.

thank you.

[Csini]

can you please correct the same issue in

<generatorName>java</generatorName>
<library>resttemplate</library>

?

[martin-mfg]

Hi @Csini, I don't have the time to make the changes for resttemplate. Please create a PR yourself, or create a new issue describing your problem and add a bounty (like e.g. here) to increase the chance of someone else working on it.

[kulon]

We upgraded from version 7.6.0 to 7.10.0 and found that changes between these versions break the java-camel generator's processing of the oneOf/anyOf definitions.

For example, the following schema generates proper code with version 7.6.0, but the generator version 7.10.0 creates a class with no fields. We are using version 3.0.3 of the OpenAPI spec.

"Request": {
      "type": "object",
      "properties": {
        "referenceNumber": {"type": "string", "nullable": true},
        "documentNumber": { "type": "string", "nullable": true},
        "stockNumber": {"type": "string", "nullable": true}
      },
      "oneOf": [
        {
          "required" : [ "referenceNumber" ]
        },
        {
          "anyOf": [
            {
              "required": [ "documentNumber" ]
            },
            {
              "required": [ "stockNumber" ]
            }
          ]
        }
      ]
    }

[martin-mfg]

Hi @kulon, I wasn't able to reproduce your problem yet. Could you please share the full openAPI spec and generator settings?

[kulon]

HI @martin-mfg, please take a look at this sample app:
https://github.com/kulon/code-samples/tree/main/openapi-generator-sample

Just changing the generator's version in the pom.xml from 7.6.0 to 7.10.0 will break the app.

[martin-mfg]

The problem occurs already in OpenAPI Generator version 7.9.0, according to my tests. i.e. it is not caused by this PR. Please open a new issue for your problem (assuming no similar issue has been opened yet).

[kulon]

Created a bug report #20312