<PackageReference Include="System.Configuration.ConfigurationManager" Version="10.0.5" />

System.Configuration.Internal.IConfigSystem

public interface IConfigSystem
Defines an interface used by .NET to support the initialization of configuration properties.
IInternalConfigHost Host { get; }

Gets the configuration host.

IInternalConfigRoot Root { get; }

Gets the root of the configuration hierarchy.

void Init(Type typeConfigHost, object[] hostInitParams)

Initializes a configuration object.