1. set a global json file
2. follow this guide : https://github.com/domaindrivendev/Swashbuckle.AspNetCore#using-the-tool-with-the-net-core-30-sdk-or-later
3. compile project
4. run dotnet swagger tofile --output v1.swagger.json ".\bin\Debug\netcoreapp3.1\SomeWebApp.dll" v1
   this should create on your project folder a file the swagger file : v1.swagger.json

References:

• main library repo
• swaggerGenerationLibrary
• more custom swagger filters
• autorest/extensions
• example
• PPT

capabilty example:

https://dev.azure.com/msazure/One/_git/DI-Agri/pullrequest/5144979 https://msazure.visualstudio.com/One/_git/DI-Agri?path=/src/PaaS/src/csharp/ResourceProviderService/Docs/arm-swagger/agfood/resource-manager/Microsoft.AgFoodPlatform/preview/2020-05-12-preview/agfood.json