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

System.Configuration.ConfigurationPropertyCollection

Represents a collection of configuration-element properties.
namespace System.Configuration { public class ConfigurationPropertyCollection : ICollection, IEnumerable { public ConfigurationProperty this[string name] { get; } public int Count { get; } public bool IsSynchronized { get; } public object SyncRoot { get; } public IEnumerator GetEnumerator(); public void CopyTo(ConfigurationProperty[] array, int index); public bool Contains(string name); public void Add(ConfigurationProperty property); public bool Remove(string name); public void Clear(); public ConfigurationPropertyCollection(); } }