[BUG][Java] OneOf-Class not generated

[hidingturtle]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

The OpenAPI Generator v5.3.1 & 5.3.0 does not generate a OneOf-Model-Class which results in the code not being able to be built. I found the exact same issue in Java jersey2, Java native (and Rust reqwest). This confuses me as the Java generators are supposed to support OneOf (#10463 (comment) and #7263). I expected the Generator to support OneOf in Java as these two links say.

openapi-generator version

5.3.1 & 5.3.0

OpenAPI declaration file content or url

https://raw.githubusercontent.com/jdegre/5GC_APIs/master/TS29510_Nnrf_NFManagement.yaml

Generation Details

(Jersey2)
java -jar openapi-generator-cli-5.3.1-20211116.151401-16.jar generate -i Desktop/5GC_APIs/TS29510_Nnrf_NFManagement.yaml -g java -o Desktop/NRFManagement_java_jersey2 --library jersey2 --additional-properties=packageName=nfmanagement

OR

(Native)
java -jar openapi-generator-cli-5.3.1-20211116.151401-16.jar generate -i Desktop/5GC_APIs/TS29510_Nnrf_NFManagement.yaml -g java -o Desktop/NRFManagement_java_native --library native --additional-properties=packageName=nfmanagement

Steps to reproduce

1. Generate Code of NFManagement with OpenAPI Generator (with Generation Details above)
2. Try to build it
3. Search for Error "Cannot resolve symbol 'OneOfNfInstanceIdCondNfInstanceIdListCondNfTypeCondServiceNameCondAmfCondGuamiListCondNetworkSliceCondNfGroupCondNfSetCondNfServiceSetCondUpfCondScpDomainCondNwdafCondNefCondDccfCond'"

Related issues/PRs

#9791
#10514
#9981

Suggest a fix

The error is caused by "TS29510_Nnrf_NFManagement.yaml" line 1449-1465. Might be worth looking into.

subscrCond:
          oneOf:
            - $ref: '#/components/schemas/NfInstanceIdCond'
            - $ref: '#/components/schemas/NfInstanceIdListCond'
            - $ref: '#/components/schemas/NfTypeCond'
            - $ref: '#/components/schemas/ServiceNameCond'
            - $ref: '#/components/schemas/AmfCond'
            - $ref: '#/components/schemas/GuamiListCond'
            - $ref: '#/components/schemas/NetworkSliceCond'
            - $ref: '#/components/schemas/NfGroupCond'
            - $ref: '#/components/schemas/NfSetCond'
            - $ref: '#/components/schemas/NfServiceSetCond'
            - $ref: '#/components/schemas/UpfCond'
            - $ref: '#/components/schemas/ScpDomainCond'
            - $ref: '#/components/schemas/NwdafCond'
            - $ref: '#/components/schemas/NefCond'
            - $ref: '#/components/schemas/DccfCond'

[millotp]

We have the same issue when generating oneOf with the Java generator, with any library.
It references an UNKNOWN_BASE_TYPE object that doesn't exists and break the compilation, can we get a progress update on this feature ? Thanks

[lpar]

It looks as if there's a problem with oneOf support for properties; as the summary indicates, the generator fails to generate the appropriate wrapper class to wrap the individual data classes.

A workaround seems to be to rewrite the spec file to introduce an explicit wrapper class. The class can use oneOf successfully.

For example, we had:

    CredentialOptions:
      type: object
      properties:
        secret:
          type: object
          additionalProperties: true
          oneOf:
            - $ref: '#/components/schemas/MiradoreCredentialFields'
            - $ref: '#/components/schemas/AWSCredentialFields'
            - $ref: '#/components/schemas/AzureClientSecretCredentialFields'
            - $ref: '#/components/schemas/AzureUsernamePasswordCredentialFields'
            - $ref: '#/components/schemas/CrowdstrikeCredentialFields'
            - $ref: '#/components/schemas/CensysCredentialFields'
            - $ref: '#/components/schemas/SNMPv2CommunitiesCredentialFields'
            - $ref: '#/components/schemas/SNMPv3CredentialFields'
            - $ref: '#/components/schemas/VMwareCredentialFields'
        [other properties omitted]

This caused code to be generated with a missing class with an extremely long name starting OneOf. I added an explicit wrapper:

    CredentialFields:
      oneOf:
        - $ref: '#/components/schemas/MiradoreCredentialFields'
        - $ref: '#/components/schemas/AWSCredentialFields'
        - $ref: '#/components/schemas/AzureClientSecretCredentialFields'
        - $ref: '#/components/schemas/AzureUsernamePasswordCredentialFields'
        - $ref: '#/components/schemas/CrowdstrikeCredentialFields'
        - $ref: '#/components/schemas/CensysCredentialFields'
        - $ref: '#/components/schemas/SNMPv2CommunitiesCredentialFields'
        - $ref: '#/components/schemas/SNMPv3CredentialFields'
        - $ref: '#/components/schemas/VMwareCredentialFields'

    CredentialOptions:
      type: object
      properties:
        secret:
          $ref: '#/components/schemas/CredentialFields'
        [other properties omitted]

...and the generated code (with --library jersey2) then includes an implementation of CredentialFields which tries deserializing to the alternatives in turn. Everything compiles.

[jafin]

Same error described above with oneOf is exhibited in the csharp-netcore generator as well.

[wing328]

jersey2, native, okhtp-gson libraries in the java generator has better support for oneOf. Please give it a try.

[dmitri-d]

There's a similar issue with go-client generator: when a oneOf is used in a field, a corresponding model isn't being generated, and the client fails to build.

[llakhch]

OneOf-Model-Classes are generating without any issue with openapi-generator-cli-6.2.1. It seems this issue has been resolved now.

[igauravsehrawat]

@llakhch
What command did you used?

I am still getting empty interface.

[srix55]

I have a question - must be basic. How do I put a oneOf type into the parent. Regular type-casting can't work as the parent is not extended by subtype. For example, PlaylistItem is one that can be oneOf PlaylistItemVideo/PlaylistItemImage etc. The classes are getting generated for PlaylistItem, PlaylistItemVideo & PlaylistItemImage. Now how do i get an object of PlaylistItemImage into PlaylistItem? Do you use ObjectMapper or something?

My example:-

PlaylistItem:
  oneOf:
    - $ref: './playlist-item-picture.yaml#/PlaylistItemPicture'
    - $ref: './playlist-item-video.yaml#/PlaylistItemVideo'
  discriminator:
    propertyName: playlistItemType
    mapping:
      picture: './playlist-item-picture.yaml#/PlaylistItemPicture'
      video: './playlist-item-video.yaml#/PlaylistItemVideo'