This issue exists when generating the Twitter API https://api.twitter.com/2/openapi.json [openapi.json.zip](https://github.com/OpenAPITools/openapi-generator/files/8644191/openapi.json.zip) ``` openapi-generator-cli 5.4.0 commit : 4a36be7 built : 2022-01-31T05:31:36Z source : https://github.com/openapitools/openapi-generator docs : https://openapi-generator.tech/ ``` ``` openapi-generator generate -i spec.json -g dart -o dart_client ``` <img width="721" alt="Screen Shot 2022-05-06 at 9 17 15 PM" src="https://user-images.githubusercontent.com/666539/167232206-d431f1e9-e2ff-4d55-b1c1-78f1cb1cea37.png"> Related to: - https://github.com/OpenAPITools/openapi-generator/issues/2567 - https://github.com/OpenAPITools/openapi-generator/pull/6913