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

System.Configuration.ConfigurationLockCollection

Contains a collection of locked configuration objects. This class cannot be inherited.
namespace System.Configuration { public sealed class ConfigurationLockCollection : ICollection, IEnumerable { public bool IsModified { get; } public string AttributeList { get; } public bool HasParentElements { get; } public int Count { get; } public bool IsSynchronized { get; } public object SyncRoot { get; } public IEnumerator GetEnumerator(); public void Add(string name); public void Remove(string name); public void Clear(); public bool Contains(string name); public void CopyTo(string[] array, int index); public bool IsReadOnly(string name); public void SetFromList(string attributeList); } }