Swagger polymorphic test

api.yaml

openapi: "3.0.0"
info:
  description: Test API
  version: "2.2.1"
  title: "Test API"


servers:
  - url: "https://this-is-a-test/eap"
    description: "API server"


paths:
  /test/datasets/:
    get:
      tags:
        - "dataset"
      summary: "Dataset definition and available snapshot resources"
      description: blah blah blah
      operationId: "getDataset"
      parameters:
        - $ref: "#/components/parameters/catalog"
        - $ref: "#/components/parameters/dataset"
      responses:
        "200":
          description: "Success"
          content:
            application/ld+json:
              schema:
                oneOf:
                  - $ref: "#/components/schemas/Dataset"
                  - $ref: "#/components/schemas/HistoryDataset"
components:
  schemas:
    Type:
      type: string
      description: "JSON-LD type"
      externalDocs:
        description: "JSON-LD definition"
        url: "https://www.w3.org/TR/json-ld/#typed-values"
    AssociatedRequest:
      type: string
      description: blah blah blah
    BaseDataset:
      type: object
      description: "A basic dataset resource."
      required:
        - "@id"
        - "@type"
        - "title"
        - "description"
        - "identifier"
        - "contains"
      properties:
        "@id":
          type: string
        "@type":
          allOf:
            - $ref: "#/components/schemas/Type"
            - enum:
                - "BaseDataset"
        "title":
          type: string
        "description":
          type: string
    Dataset:
      allOf:
        - $ref: "#/components/schemas/BaseDataset"
        - type: object
          description: "A dataset resource."
          required:
            - "@type"
          properties:
            "@type":
              allOf:
                - $ref: "#/components/schemas/Type"
                - enum:
                    - "Dataset"
            "request":
              $ref: "#/components/schemas/AssociatedRequest"
    HistoryDataset:
      allOf:
        - $ref: "#/components/schemas/BaseDataset"
        - type: object
          description: blah blah blah
          required:
            - "@type"
          properties:
            "@type":
              allOf:
                - $ref: "#/components/schemas/Type"
                - enum:
                    - "HistoryDataset"
            "request":
              $ref: "#/components/schemas/AssociatedRequest"
  parameters:
    catalog:
      name: "catalog"
      in: "path"
      description: blah blah blah
      required: true
      schema:
        type: "string"
    dataset:
      name: "dataset"
      in: "path"
      description: "Dataset identifier"
      required: true
      schema:
        type: "string"

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>swagger-dev-test</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>

        <swagger-core-version>2.1.11</swagger-core-version>
    </properties>


    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.fasterxml.jackson</groupId>
                <artifactId>jackson-bom</artifactId>
                <version>2.12.5</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>io.swagger.core.v3</groupId>
            <artifactId>swagger-annotations</artifactId>
            <version>${swagger-core-version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish</groupId>
            <artifactId>javax.annotation</artifactId>
            <version>3.1.1</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter</artifactId>
            <version>5.8.2</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>io.swagger.codegen.v3</groupId>
                <artifactId>swagger-codegen-maven-plugin</artifactId>
                <version>3.0.30</version>
                <dependencies>
                    <dependency>
                        <groupId>io.swagger.codegen.v3</groupId>
                        <artifactId>swagger-codegen-cli</artifactId>
                        <!-- This is the custom JAR you gave me! -->
                        <version>poly-SNAPSHOT</version>
                    </dependency>
                </dependencies>
                <executions>
                    <execution>
                        <id>generate-model</id>
                        <!-- This generates only the models, because we want to use jersey -->
                        <goals>
                            <goal>generate</goal>
                        </goals>
                        <configuration>
                            <inputSpec>${project.basedir}/src/main/resources/api.yaml</inputSpec>
                            <language>java</language>
                            <configOptions>
                                <sourceFolder>src/gen/java/main</sourceFolder>
                                <library>jersey2</library>
                                <apiPackage>com.testing.api</apiPackage>
                                <modelPackage>com.testing.model</modelPackage>
                                <java11>true</java11>
                                <dateLibrary>java8</dateLibrary>
                            </configOptions>
                            <generateModels>true</generateModels>
                            <generateApis>false</generateApis>
                            <generateModelDocumentation>false</generateModelDocumentation>
                            <generateSupportingFiles>false</generateSupportingFiles>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

TestDataset.java

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.testing.model.Dataset;
import com.testing.model.OneOfinlineResponse200;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

public class TestDataset {
    @Test
    public void testDataset() throws JsonProcessingException {
        Dataset dataset = new Dataset();
        dataset.setDatasetAtType("Dataset"); //Mandated by the spec, but whatever.
        dataset.setRequest("request");
        dataset.setAtId("id");
        //This is impossible:
        //dataset.setAtType(new AnyOfBaseDatasetAtType() {});

        ObjectMapper om = new ObjectMapper();
        String val = om.writeValueAsString(dataset);
        OneOfinlineResponse200 response200 = om.readValue(val, OneOfinlineResponse200.class);

        Assertions.assertEquals(dataset, response200);
    }
}