<PackageReference Include="System.Configuration.ConfigurationManager" Version="10.0.2" />

System.Configuration.SchemeSettingElementCollection

Represents a collection of SchemeSettingElement objects.
namespace System.Configuration { public sealed class SchemeSettingElementCollection : ConfigurationElementCollection { public SchemeSettingElement this[int index] { get; } public new SchemeSettingElement this[string name] { get; } public SchemeSettingElementCollection(); public int IndexOf(SchemeSettingElement element); } }