title: How to use OpenAPI "oneOf" property with openapi-generator-maven-plugin when generating Spring code
body: <p>I am developing an application with an Angular frontend and RESTful Spring Boot Backend</p>
  <p>I found this very handy maven plugin <a href="https://openapi-generator.tech/docs/generators/spring/" rel="noreferrer">openapi-generator-maven-plugin</a> from org.openapitools. With its code generation capability, it helps enforce a &quot;contract first&quot; approach between the frontend and backend for our API. But our swagger file uses &quot;oneOf&quot; property in the requestBody and responseBody definitions. I've tried to generate Spring code from this, but the generated Java class has missing imports:</p>
  <pre><code>import com.pack.api.dto.OneOfLatteCoffeAmericanoCoffe;
  import com.pack.api.dto.UNKNOWN_BASE_TYPE;
  </code></pre>
  <p>Is there away to cofigue the plugin to work with Swagger's oneOf property? I'm usig Spring Boot 2.3.1, Swagger 3.0 and Openapi-generator-maven-plugin 4.3</p>