Java generated code does not implement discriminator mappings correctly

[helderdiniz]

The current version of swagger-codegen generates inconsistent discriminator mappings for Jackson's JsonSubTypes annotations for different Java modules. I'm currently using swagger-codegen to generate model classes, REST controller interfaces using OpenAPI 3.0 definitions. We're using the maven plugin generator facility in order to generate both Spring controllers, as well as java-clients using resttemplate library. However, we've noticed inconsistencies between SpringCodegen classes and JavaClientCodegen classes for the same API definitions.

Versions

This is currently happening on 3.0.23, both on Maven plugin & CLI.

Reproduction Details

The following API definition was used to reproduce this issue

openapi: '3.0.3'
info:
  title: 'Discriminator Problem API'
  version: '1.0.0'

components:
  schemas:
    SomeTypeDTO:
      type: string
      enum:
        - SubTypeA
        - WeirdlyNamedSubTypeB

    ResultForSubTypeDTO:
      type: object
      properties:
        type:
          type: string
      oneOf:
        - $ref: '#/components/schemas/SubTypeAResultDTO'
        - $ref: '#/components/schemas/SubTypeBResultDTO'
      required:
        - type
      discriminator:
        propertyName: type
        mapping:
          SubTypeA: '#/components/schemas/SubTypeAResultDTO'
          WeirdlyNamedSubTypeB: '#/components/schemas/SubTypeBResultDTO'

    SubTypeAResultDTO:
      allOf:
        - $ref: '#/components/schemas/ResultForSubTypeDTO'
      type: object
      properties:
        some_attribute:
          type: string

    SubTypeBResultDTO:
      allOf:
        - $ref: '#/components/schemas/ResultForSubTypeDTO'
      type: object
      properties:
        another_attribute:
          type: string

paths:
  /repro:
    get:
      operationId: 'getRepro'
      responses:
        204:
          description: OK

Execution

The testing was grounded on using the CLI, triggered for Java language (-l java + resttemplate library) and Spring (-l spring).

Output

Spring

@Validated
@javax.annotation.Generated(value = "io.swagger.codegen.v3.generators.java.SpringCodegen", date = "2020-11-16T16:49:29.361700Z[Europe/Lisbon]")
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type", visible = true )
@JsonSubTypes({
        @JsonSubTypes.Type(value = SubTypeAResultDTO.class, name = "SubTypeA"),
        @JsonSubTypes.Type(value = SubTypeBResultDTO.class, name = "WeirdlyNamedSubTypeB"),
})

public class ResultForSubTypeDTO  implements Serializable , OneOfResultForSubTypeDTO  {
// Redacted
}

Works as expected, having the SubTypeAResultDTO and SubTypeBResultDTO classes properly mapped to its discriminator definition.

Java Client

@javax.annotation.Generated(value = "io.swagger.codegen.v3.generators.java.JavaClientCodegen", date = "2020-11-16T16:39:57.004152Z[Europe/Lisbon]")  
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type", visible = true )
  @JsonSubTypes({
      @JsonSubTypes.Type(value = SubTypeAResultDTO.class, name = "SubTypeAResultDTO"),
      @JsonSubTypes.Type(value = SubTypeBResultDTO.class, name = "SubTypeBResultDTO"),
  })
public class ResultForSubTypeDTO implements Serializable, OneOfResultForSubTypeDTO {
// Redacted
 }

Generates erroneous code, discarding the existing discriminator mapping for SubTypeAResultDTOandSubTypeBResultDTO` classes.

Expected

The expected behavior is that the generation for the Java Client code should contain the correct discriminator mapping, as following

@JsonSubTypes({
        @JsonSubTypes.Type(value = SubTypeAResultDTO.class, name = "SubTypeA"),
        @JsonSubTypes.Type(value = SubTypeBResultDTO.class, name = "WeirdlyNamedSubTypeB"),
})

---

Note: This is a similar issue introduced at #602, but the PR (#603) related to that issue only fixed the problem for Spring, leaving other Java modules outdated, such as Micronaut, JavaClient or JAXRS.

[bdotzour]

I feel like this may be the right place to also mention that the generator code for SubTypes does not take into account model name prefixes or suffixes and instead uses the Schema name. Would it be possible to address that problem at the same time as well?

[felipebn]

I'm currently hitting that very same issue, is there any follow up on this or workaround?

I see the PR got stale since some time as the issue too.

[HugoMario]

fixed by #12302