<PackageReference Include="System.Configuration.ConfigurationManager" Version="10.0.0" />

System.Configuration.NameValueFileSectionHandler

Provides access to a configuration file. This type supports the .NET configuration infrastructure and is not intended to be used directly from your code.
namespace System.Configuration { public class NameValueFileSectionHandler : IConfigurationSectionHandler { public object Create(object parent, object configContext, XmlNode section); public NameValueFileSectionHandler(); } }