<PackageReference Include="System.Security.AccessControl" Version="6.0.0-preview.4.21253.7" />

System.Diagnostics.CodeAnalysis.MemberNotNullWhenAttribute

namespace System.Diagnostics.CodeAnalysis { internal sealed class MemberNotNullWhenAttribute : Attribute { public bool ReturnValue { get; } public string[] Members { get; } public MemberNotNullWhenAttribute(bool returnValue, string member); public MemberNotNullWhenAttribute(bool returnValue, params string[] members); } }