[BUG][KOTLIN-SPRING] Constructor call generated for interface supertypes if using inheritance/discriminator

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?
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Description

If the parent of a type is generated as interface the subtype is generated with a constructor call to the parent interface which doesn't compile:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type", visible = true)
@JsonSubTypes(
      JsonSubTypes.Type(value = SubtypeA::class, name = "subtypeA"),
      JsonSubTypes.Type(value = SubtypeB::class, name = "subtypeB")
)
interface ParentSchema{
        val id: kotlin.String
        val type: DiscriminatingType
}

data class SubtypeA(

    @get:NotNull  
    @field:JsonProperty("id") override val id: kotlin.String,

    @get:NotNull  
    @field:Valid
    @field:JsonProperty("type") override val type: DiscriminatingType,

    @field:JsonProperty("subtypeAproperty") val subtypeAproperty: kotlin.Int? = null
) : ParentSchema(){
  
}

Note: ParentSchema(). The () prevent compilation

openapi-generator version

openapi-generator-maven-plugin:5.0.0

OpenAPI declaration file content or url

Sample spec

Related issues/PRs

Similar: #3587

Suggest a fix

I worked around it by removing the () from dataClass.mustache. This wouldn't work if the parent is a class.

Start with dataClass.mustache and the linked sample OpenAPI specification, then generate the Kotlin Spring models to reproduce the ParentSchema interface case. Compare the generated subtype declaration for interface and class parents; done means the interface case no longer emits ParentSchema() and the generated Kotlin compiles without breaking class inheritance.