<PackageReference Include="System.Configuration.ConfigurationManager" Version="7.0.0-preview.4.22229.4" />

SettingsAttributeDictionary

using System.Collections; using System.Runtime.Serialization; namespace System.Configuration { public class SettingsAttributeDictionary : Hashtable { public SettingsAttributeDictionary() { } public SettingsAttributeDictionary(SettingsAttributeDictionary attributes) : base(attributes) { } protected SettingsAttributeDictionary(SerializationInfo serializationInfo, StreamingContext streamingContext) : base(serializationInfo, streamingContext) { throw new PlatformNotSupportedException(); } } }