enable summarize capabilities.

src/libraries/Microsoft.PowerFx.Core/Entities/External/TableDelegationInfo.cs

@@ -22,7 +22,7 @@ public abstract class TableDelegationInfo
         // Used to indicate whether this table has selectable columns
         public SelectionRestrictions SelectionRestriction { get; init; }
 
-        public SummarizeRestrictions SummarizeRestriction { get; init; }
+        public SummarizeCapabilities SummarizeCapabilities { get; init; }
 
         // Defines ungroupable columns
         public GroupRestrictions GroupRestriction { get; init; }
@@ -264,16 +264,19 @@ public SelectionRestrictions()
         }
     }
 
-    public sealed class SummarizeRestrictions
+    public class SummarizeCapabilities
     {
-        /// <summary>
-        /// List of properties that can not be summarized.
-        /// </summary>
-        public ICollection<string> NonSummarizableProperties { get; init; }
-
-        public ICollection<SummarizeMethod> NotSupportedSummarizeMethods { get; init; }
-
-        public SummarizeRestrictions()
+        public virtual bool IsSummarizableProperty(string propertyName)
+        {
+            return false;
+        }
+
+        public virtual bool IsSummarizableMethod(SummarizeMethod method)
+        {
+            return false;
+        }
+
+        public SummarizeCapabilities()
         {
         }
     }

src/libraries/Microsoft.PowerFx.Core/Public/Values/DelegationParameters.cs

@@ -73,6 +73,9 @@ public enum DelegationParameterFeatures
         // $apply
         Apply = 1 << 4,
 
+        // $apply = groupby((field1, ..), fileld with sum as TotoalSum)
+        ApplyGroupBy = 1 << 5,
+
         /*
           To be implemented later when needed