Index: Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Plugin/HeightStructuresPlugin.cs
===================================================================
diff -u -r9e6869de553715aefe4752478334c3a6a3f83340 -r964f8948f0ec59095ea9cc58fdabd706c4b17d22
--- Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Plugin/HeightStructuresPlugin.cs	(.../HeightStructuresPlugin.cs)	(revision 9e6869de553715aefe4752478334c3a6a3f83340)
+++ Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Plugin/HeightStructuresPlugin.cs	(.../HeightStructuresPlugin.cs)	(revision 964f8948f0ec59095ea9cc58fdabd706c4b17d22)
@@ -381,7 +381,7 @@
             };
         }
 
-        private static IList GetInputs(HeightStructuresFailureMechanism failureMechanism, IAssessmentSection assessmentSection)
+        private static IEnumerable GetInputs(HeightStructuresFailureMechanism failureMechanism, IAssessmentSection assessmentSection)
         {
             return new ArrayList
             {
@@ -392,7 +392,7 @@
             };
         }
 
-        private static IList GetOutputs(HeightStructuresFailureMechanism failureMechanism)
+        private static IEnumerable GetOutputs(HeightStructuresFailureMechanism failureMechanism)
         {
             return new ArrayList
             {
@@ -607,7 +607,7 @@
             };
         }
 
-        private void UpdateStructureDependentDataOfCalculations(IList<StructuresCalculation<HeightStructuresInput>> calculations)
+        private void UpdateStructureDependentDataOfCalculations(IEnumerable<StructuresCalculation<HeightStructuresInput>> calculations)
         {
             string message = RingtoetsCommonFormsResources.VerifyUpdate_Confirm_calculation_outputs_cleared;
             if (StructureDependentDataShouldUpdate(calculations, message))