<PackageReference Include="NETStandard.Library" Version="2.0.0" />

System.ComponentModel.Design.DesignerCollection

namespace System { public sealed class ObsoleteAttribute : Attribute { public bool IsError { get; } public string Message { get; } public ObsoleteAttribute(); public ObsoleteAttribute(string message); public ObsoleteAttribute(string message, bool error); } } namespace System.ComponentModel.Design { public class DesignerCollection : ICollection, IEnumerable { public int Count { get; } public virtual IDesignerHost this[int index] { get; } public DesignerCollection(IList designers); public DesignerCollection(IDesignerHost[] designers); public IEnumerator GetEnumerator(); } }