<PackageReference Include="Newtonsoft.Json" Version="13.0.4" />

System.Diagnostics.CodeAnalysis.FeatureGuardAttribute

Indicates that the specified public static boolean get-only property guards access to the specified feature.
namespace System.Diagnostics.CodeAnalysis { internal sealed class FeatureGuardAttribute : Attribute { public Type FeatureType { get; } public FeatureGuardAttribute(Type featureType); } }