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

System.Configuration.SettingsPropertyValueCollection

Contains a collection of settings property values that map SettingsProperty objects to SettingsPropertyValue objects.
namespace System.Configuration { public class SettingsPropertyValueCollection : IEnumerable, ICloneable, ICollection { public SettingsPropertyValue this[string name] { get; } public int Count { get; } public bool IsSynchronized { get; } public object SyncRoot { get; } public SettingsPropertyValueCollection(); public void Add(SettingsPropertyValue property); public void Remove(string name); public IEnumerator GetEnumerator(); public object Clone(); public void SetReadOnly(); public void Clear(); public void CopyTo(Array array, int index); } }