Export API Definition
https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-export-api.html
in openapi 3
aws apigateway get-export --parameters extensions='apigateway' --rest-api-id <id> --stage-name preprod --export-type oas30 export.json
in swagger
aws apigateway get-export --parameters extensions='apigateway' --rest-api-id <id> --stage-name preprod --export-type swagger swagger.json