fix: add ISelectableItems<TKey,TValue> interface

src/PepperDash.Essentials.Core/DeviceTypeInterfaces/ISelectableItems.cs

@@ -4,19 +4,24 @@ using System.Collections.Generic;
 
 namespace PepperDash.Essentials.Core.DeviceTypeInterfaces
 {
-    /// <summary>
+    public interface ISelectableItems<TKey, TValue> where TValue : ISelectableItem
-    /// Describes a collection of items that can be selected
-    /// </summary>
-    /// <typeparam name="TKey">type for the keys in the collection.  Probably a string or enum</typeparam>
-    public interface ISelectableItems<TKey>
     {
         event EventHandler ItemsUpdated;
         event EventHandler CurrentItemChanged;
 
         [JsonProperty("items")]
-        Dictionary<TKey, ISelectableItem> Items { get; set; }
+        Dictionary<TKey, TValue> Items { get; set; }
 
         [JsonProperty("currentItem")]
         TKey CurrentItem { get; set; }
+
+    }
+
+    /// <summary>
+    /// Describes a collection of items that can be selected
+    /// </summary>
+    /// <typeparam name="TKey">type for the keys in the collection.  Probably a string or enum</typeparam>
+    public interface ISelectableItems<TKey> : ISelectableItems<TKey, ISelectableItem>
+    {        
     }
 }