<PackageReference Include="System.Configuration.ConfigurationManager" Version="7.0.0-preview.2.22152.2" />

IConfigurationSectionHandler

public interface IConfigurationSectionHandler
The IConfigurationSectionHandler interface defines the contract that all configuration section handlers must implement in order to participate in the resolution of configuration settings. Composes and creates config objects. This interface is implemented by config providers. Classes implementing IConfigurationSectionHandler define the rules for cooking XML config into usable objects. The cooked objects can be of arbitrary type. Configuration is composable (e.g., config in a child directory is layered over config in a parent directory), so, IConfigurationSectionHandler is supplied with the parent config as well as any number of XML fragments.
using System.Xml; namespace System.Configuration { public interface IConfigurationSectionHandler { object Create(object parent, object configContext, XmlNode section); } }