Force combination was added

StructureHelperCommon/Models/Calculators/IHelperCalculator.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperCommon.Models.Calculators
+{
+    public interface IHelperCalculator <in TInputData, TCalculationResult>
+        where TInputData : class
+        where TCalculationResult : class
+    {
+    }
+}