AngleSharp by AngleSharp

<PackageReference Include="AngleSharp" Version="0.17.1" />

 NotNullIfNotNullAttribute

using System.Runtime.CompilerServices; namespace System.Diagnostics.CodeAnalysis { [System.Runtime.CompilerServices.NullableContext(1)] [System.Runtime.CompilerServices.Nullable(0)] internal sealed class NotNullIfNotNullAttribute : Attribute { public string ParameterName { get; } public NotNullIfNotNullAttribute(string parameterName) { ParameterName = parameterName; } } }