<PackageReference Include="NETStandard.Library" Version="2.0.0-preview2-25401-01" />

System.Dynamic.ExpandoObject

public sealed class ExpandoObject : ICollection<KeyValuePair<string, object>>, IEnumerable<KeyValuePair<string, object>>, IEnumerable, IDictionary<string, object>, INotifyPropertyChanged, IDynamicMetaObjectProvider
namespace System.Dynamic { public sealed class ExpandoObject : ICollection<KeyValuePair<string, object>>, IEnumerable<KeyValuePair<string, object>>, IEnumerable, IDictionary<string, object>, INotifyPropertyChanged, IDynamicMetaObjectProvider { object IDictionary<string, object>.this[string key] { get; set; } event PropertyChangedEventHandler INotifyPropertyChanged.PropertyChanged; public ExpandoObject(); } }