How to implement Java Interface classes in Open API Template

Output class is generated as 

@Generated(value = "org.openapitools.codegen.languages.SpringCodegen")
public class GetEntitiesResponse {
  @JsonProperty("convertedCurrency")
  private String convertedCurrency;

  @JsonProperty("entities")
  @Valid
  private List<Entity> entities = null;

  @JsonProperty("showEntityAccountsinSingleView")
  private Boolean showEntityAccountsinSingleView;
}

instead of required Class

public class GetEntitiesAndAccountsResponse implements ServiceCodeOverride, EntityServiceCodeOverride {
   String convertedCurrency;
   List<Entity> entities;
   boolean showEntityAccountsinSingleView;

}

build.gradle configuration:

openApiGenerate {
    generatorName = "spring"
    inputSpec = project.ext.openApiSpecFile.toString()
    outputDir = "${generatedModelDir}"
    modelPackage = "com.example.dto"
    configOptions = [
            dateLibrary: "java8", // dateLibrary option is set to java8, which specifies that the java.time classes should be used for date/time handling
            useLombok: "true", // Enable Lombok
            interfaceImplementation: "true"
    ]
}

following is openApi Template for the class

"GetEntitiesResponse": {
  "x-java-implements": [
    "com.example.dto.ServiceCodeOverride",
    "com.example.dto.EntityServiceCodeOverride"
  ],

      "type": "object",
      "properties": {
        "convertedCurrency": {
          "type": "string"
        },
        "entities": {
          "type": "array",
          "items": {
            "$ref": "#/components/schemas/Entity"
          }
        },
        "showEntityAccountsinSingleView": {
          "type": "boolean"
        }
      }
},

How to get the required output class with implementation of interfaces.