aqua.tool.polyfill.Nullable (nuget): C# source code only package which allows you to use .NET's new nullable attributes and assertion method to check for null values.  This package is an extension to https://www.nuget.org/packages/Nullable/.  The C# code is only included if targeting a framework version which does not already cover nullable attributes.  Requires C# 8.0 or later.
Keywords: c#|csharp|nullable