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Can I use C#9.0 with ASP.NET Core 3.1?https://www.reddit.com/r/csharp/comments/kiplz8/can_i_use_c90_with_aspnet_core_31/
manuelroemer/IsExternalInitUse C# 9's init and record features in in older target frameworks.https://github.com/manuelroemer/IsExternalInit