message: feat: support for x-discriminator-value for 2.0 as alternative to mapping
  Add vendor extension `x-discriminator-value `used by swagger-codegen for Swagger 2.0 as an alternative to OpenAPI 3.0 mapping feature.
diff: @@ -280,7 +280,7 @@ export class OpenAPIParser {
  def.allOf !== undefined &&
  def.allOf.find(obj => obj.$ref !== undefined && $refs.indexOf(obj.$ref) > -1)
  ) {
  - res['#/components/schemas/' + defName] = defName;
  + res['#/components/schemas/' + defName] = def['x-discriminator-value'] || defName;
  }
  }
  return res;
  