<PackageReference Include="System.Configuration.ConfigurationManager" Version="10.0.0-rc.1.25451.107" />

System.Configuration.SettingsBase

public abstract class SettingsBase
Provides the base class used to support user property settings.
namespace System.Configuration { public abstract class SettingsBase { public virtual object this[string propertyName] { get; set; } public virtual SettingsPropertyCollection Properties { get; } public virtual SettingsProviderCollection Providers { get; } public virtual SettingsPropertyValueCollection PropertyValues { get; } public virtual SettingsContext Context { get; } public bool IsSynchronized { get; } protected SettingsBase(); public void Initialize(SettingsContext context, SettingsPropertyCollection properties, SettingsProviderCollection providers); public virtual void Save(); public static SettingsBase Synchronized(SettingsBase settingsBase); } }