<PackageReference Include="System.Configuration.ConfigurationManager" Version="10.0.1" />

System.Configuration.SettingChangingEventHandler

public sealed delegate SettingChangingEventHandler : MulticastDelegate
Represents the method that will handle the SettingChanging event.
public SettingChangingEventHandler(object object, IntPtr method)

public virtual IAsyncResult BeginInvoke(object sender, SettingChangingEventArgs e, AsyncCallback callback, object object)

public virtual void EndInvoke(IAsyncResult result)

public virtual void Invoke(object sender, SettingChangingEventArgs e)