Added IHasExtraProperties

src/Volo.Abp.Data/Volo/Abp/Data/IHasExtraProperties.cs

@@ -0,0 +1,9 @@
+using System.Collections.Generic;
+
+namespace Volo.Abp.Data
+{
+    public interface IHasExtraProperties
+    {
+        Dictionary<string, object> ExtraProperties { get; }
+    }
+}