Index: Core/Common/src/Core.Common.Base/Observable.cs
===================================================================
diff -u -r07f3d67fe9512b3c8303ff09398b0a234900d546 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Core/Common/src/Core.Common.Base/Observable.cs	(.../Observable.cs)	(revision 07f3d67fe9512b3c8303ff09398b0a234900d546)
+++ Core/Common/src/Core.Common.Base/Observable.cs	(.../Observable.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -33,7 +33,7 @@
         /// <summary>
         /// The observers that are attached.
         /// </summary>
-        protected ICollection<IObserver> observers = new Collection<IObserver>();
+        protected Collection<IObserver> observers = new Collection<IObserver>();
 
         public IEnumerable<IObserver> Observers
         {
Index: Core/Common/src/Core.Common.Base/ObservableList.cs
===================================================================
diff -u -r07f3d67fe9512b3c8303ff09398b0a234900d546 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Core/Common/src/Core.Common.Base/ObservableList.cs	(.../ObservableList.cs)	(revision 07f3d67fe9512b3c8303ff09398b0a234900d546)
+++ Core/Common/src/Core.Common.Base/ObservableList.cs	(.../ObservableList.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -34,7 +34,7 @@
         /// <summary>
         /// The observers that are attached.
         /// </summary>
-        protected ICollection<IObserver> observers = new Collection<IObserver>();
+        protected Collection<IObserver> observers = new Collection<IObserver>();
 
         public IEnumerable<IObserver> Observers
         {
Index: Core/Common/src/Core.Common.Controls.TreeView/TreeViewControl.cs
===================================================================
diff -u -r0ec4972fb80e931795d6d60fc659169b558ea28d -r61c2ac2573d82151b0b1593260a419543d07122a
--- Core/Common/src/Core.Common.Controls.TreeView/TreeViewControl.cs	(.../TreeViewControl.cs)	(revision 0ec4972fb80e931795d6d60fc659169b558ea28d)
+++ Core/Common/src/Core.Common.Controls.TreeView/TreeViewControl.cs	(.../TreeViewControl.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -666,7 +666,7 @@
             parentNode.Nodes.Insert(newChildNodeIndex, existingTreeNode);
         }
 
-        private void InsertNewChildNodeAtIndex(TreeNode parentNode, int childNodeIndex, object expectedChildNodeData, ICollection<TreeNode> newlyAddedTreeNodes)
+        private void InsertNewChildNodeAtIndex(TreeNode parentNode, int childNodeIndex, object expectedChildNodeData, List<TreeNode> newlyAddedTreeNodes)
         {
             TreeNode newTreeNode = CreateTreeNode(parentNode, expectedChildNodeData);
 
Index: Core/Common/src/Core.Common.Gui/PropertyBag/DynamicPropertyBag.cs
===================================================================
diff -u -r48e2db6c910f4ec279d2d63fbb1cc05a1196b7f1 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Core/Common/src/Core.Common.Gui/PropertyBag/DynamicPropertyBag.cs	(.../DynamicPropertyBag.cs)	(revision 48e2db6c910f4ec279d2d63fbb1cc05a1196b7f1)
+++ Core/Common/src/Core.Common.Gui/PropertyBag/DynamicPropertyBag.cs	(.../DynamicPropertyBag.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -60,20 +60,23 @@
                 throw new ArgumentNullException(nameof(propertyObject));
             }
 
-            Properties = new HashSet<PropertySpec>();
-            WrappedObject = propertyObject;
-
+            var properties = new HashSet<PropertySpec>();
             foreach (PropertyInfo propertyInfo in propertyObject.GetType().GetProperties()
                                                                 .OrderBy(x => x.MetadataToken))
             {
-                Properties.Add(new PropertySpec(propertyInfo));
+                properties.Add(new PropertySpec(propertyInfo));
             }
+
+            Properties = properties;
+            WrappedObject = propertyObject;
+
+            
         }
 
         /// <summary>
-        /// Gets the collection of properties contained within this <see cref="DynamicPropertyBag"/>.
+        /// Gets the set of properties contained within this <see cref="DynamicPropertyBag"/>.
         /// </summary>
-        public ICollection<PropertySpec> Properties { get; }
+        public IEnumerable<PropertySpec> Properties { get; }
 
         /// <summary>
         /// Gets the object wrapped inside this <see cref="DynamicPropertyBag"/>.
@@ -133,7 +136,7 @@
 
         public PropertyDescriptor GetDefaultProperty()
         {
-            return Properties.Count > 0 ? new PropertySpecDescriptor(Properties.First(), WrappedObject) : null;
+            return Properties.Any() ? new PropertySpecDescriptor(Properties.First(), WrappedObject) : null;
         }
 
         public PropertyDescriptorCollection GetProperties()
Index: Core/Common/src/Core.Common.IO/Readers/ReadResult.cs
===================================================================
diff -u -r67284323e2785c651633d9c52049ba12a9c70e6a -r61c2ac2573d82151b0b1593260a419543d07122a
--- Core/Common/src/Core.Common.IO/Readers/ReadResult.cs	(.../ReadResult.cs)	(revision 67284323e2785c651633d9c52049ba12a9c70e6a)
+++ Core/Common/src/Core.Common.IO/Readers/ReadResult.cs	(.../ReadResult.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -27,7 +27,7 @@
     /// This class can be used in importers to return a result from a method where some critical error
     /// may have occurred. The type of items which are collected is supplied by <typeparamref name="T"/>.
     /// </summary>
-    /// <typeparam name="T">The type of the items which are returned in this result as <see cref="ICollection{T}"/>.</typeparam>
+    /// <typeparam name="T">The type of the items which are returned in this result as <see cref="IEnumerable{T}"/>.</typeparam>
     public class ReadResult<T>
     {
         /// <summary>
@@ -43,9 +43,9 @@
         }
 
         /// <summary>
-        /// Gets or sets the <see cref="ICollection{T}"/> of items that were read.
+        /// Gets or sets the <see cref="IEnumerable{T}"/> of items that were read.
         /// </summary>
-        public ICollection<T> Items { get; set; }
+        public IEnumerable<T> Items { get; set; }
 
         /// <summary>
         /// Gets the <see cref="bool"/> representing whether an critical error has occurred during
Index: Core/Common/test/Core.Common.Gui.Test/PropertyBag/DynamicPropertyBagTest.cs
===================================================================
diff -u -redb617ef7d51ddd52ed0b0095e679106925a837c -r61c2ac2573d82151b0b1593260a419543d07122a
--- Core/Common/test/Core.Common.Gui.Test/PropertyBag/DynamicPropertyBagTest.cs	(.../DynamicPropertyBagTest.cs)	(revision edb617ef7d51ddd52ed0b0095e679106925a837c)
+++ Core/Common/test/Core.Common.Gui.Test/PropertyBag/DynamicPropertyBagTest.cs	(.../DynamicPropertyBagTest.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -70,7 +70,7 @@
             var dynamicPropertyBag = new DynamicPropertyBag(propertyObject);
 
             // Assert
-            Assert.AreEqual(4, dynamicPropertyBag.Properties.Count, "Expected property count wrong");
+            Assert.AreEqual(4, dynamicPropertyBag.Properties.Count(), "Expected property count wrong");
         }
 
         [Test]
@@ -428,7 +428,7 @@
             PropertyDescriptorCollection properties = PropertiesTestHelper.GetAllVisiblePropertyDescriptors(propertyObject);
 
             // Assert
-            Assert.Less(properties.Count, dynamicPropertyBag.Properties.Count);
+            Assert.Less(properties.Count, dynamicPropertyBag.Properties.Count());
             Assert.IsNull(properties.Find("Name", false),
                           "Name is dynamically not browsable, therefore should not be returned.");
             Assert.IsNotNull(properties.Find("Description", false));
@@ -454,7 +454,7 @@
             });
 
             // Assert
-            Assert.Less(properties.Count, dynamicPropertyBag.Properties.Count);
+            Assert.Less(properties.Count, dynamicPropertyBag.Properties.Count());
             Assert.IsNotNull(properties.Find("Name", false),
                              "Name is dynamically not browsable, therefore should be returned.");
             Assert.IsNull(properties.Find("Description", false));
Index: Core/Components/test/Core.Components.DotSpatial.Test/Layer/BruTile/BruTileLayerTest.cs
===================================================================
diff -u -r67284323e2785c651633d9c52049ba12a9c70e6a -r61c2ac2573d82151b0b1593260a419543d07122a
--- Core/Components/test/Core.Components.DotSpatial.Test/Layer/BruTile/BruTileLayerTest.cs	(.../BruTileLayerTest.cs)	(revision 67284323e2785c651633d9c52049ba12a9c70e6a)
+++ Core/Components/test/Core.Components.DotSpatial.Test/Layer/BruTile/BruTileLayerTest.cs	(.../BruTileLayerTest.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -961,7 +961,7 @@
                 Level = level;
             }
 
-            public ICollection<TileInfoConfig> TileInfoConfigurations { get; }
+            public IEnumerable<TileInfoConfig> TileInfoConfigurations { get; }
             public int Level { get; }
         }
 
Index: Demo/Ringtoets/src/Demo.Ringtoets/Commands/AddNewDemoAssessmentSectionCommand.cs
===================================================================
diff -u -r05f3fd4c3a60e900788ebc333fa609136a639725 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Demo/Ringtoets/src/Demo.Ringtoets/Commands/AddNewDemoAssessmentSectionCommand.cs	(.../AddNewDemoAssessmentSectionCommand.cs)	(revision 05f3fd4c3a60e900788ebc333fa609136a639725)
+++ Demo/Ringtoets/src/Demo.Ringtoets/Commands/AddNewDemoAssessmentSectionCommand.cs	(.../AddNewDemoAssessmentSectionCommand.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -197,109 +197,109 @@
             const double targetProbability = 1.0 / 200000;
             ObservableList<HydraulicBoundaryLocation> locations = failureMechanism.HydraulicBoundaryLocations;
             GeneralResult<TopLevelSubMechanismIllustrationPoint> generalResult = null;
-            locations.ElementAt(0).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[0].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.19,
                 targetProbability, 4.79014,
                 1.0 / 1196727, 4.78959,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(1).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[1].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.19,
                 targetProbability, 4.79014,
                 1.0 / 1196727, 4.78959,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(2).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[2].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.18,
                 targetProbability, 4.79014,
                 1.0 / 1196727, 4.78959,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(3).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[3].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.18,
                 targetProbability, 4.79014,
                 1.0 / 1196787, 4.78960,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(4).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[4].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.18,
                 targetProbability, 4.79014,
                 1.0 / 1196787, 4.78960,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(5).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[5].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.39,
                 targetProbability, 4.79014,
                 1.0 / 1196489, 4.78955,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(6).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[6].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.39,
                 targetProbability, 4.79014,
                 1.0 / 1196489, 4.78955,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(7).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[7].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.39,
                 targetProbability, 4.79014,
                 1.0 / 1196489, 4.78955,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(8).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[8].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.40,
                 targetProbability, 4.79014,
                 1.0 / 1196489, 4.78955,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(9).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[9].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.40,
                 targetProbability, 4.79014,
                 1.0 / 1196429, 4.78954,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(10).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[10].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.40,
                 targetProbability, 4.79014,
                 1.0 / 1196429, 4.78954,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(11).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[11].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.40,
                 targetProbability, 4.79014,
                 1.0 / 1196429, 4.78954,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(12).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[12].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.40,
                 targetProbability, 4.79014,
                 1.0 / 1196429, 4.78954,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(13).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[13].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.41,
                 targetProbability, 4.79014,
                 1.0 / 1196429, 4.78954,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(14).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[14].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.41,
                 targetProbability, 4.79014,
                 1.0 / 1196429, 4.78954,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(15).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[15].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 6.91,
                 targetProbability, 4.79014,
                 1.0 / 1197264, 4.78968,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(16).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[16].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.53,
                 targetProbability, 4.79014,
                 1.0 / 1195476, 4.78938,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(17).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[17].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 7.80,
                 targetProbability, 4.79014,
                 1.0 / 1194761, 4.78926,
@@ -312,109 +312,109 @@
             const double targetProbability = 1.0 / 200000;
             ObservableList<HydraulicBoundaryLocation> locations = failureMechanism.HydraulicBoundaryLocations;
             GeneralResult<TopLevelSubMechanismIllustrationPoint> generalResult = null;
-            locations.ElementAt(0).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[0].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.99,
                 targetProbability, 4.79014,
                 1.0 / 1199892, 4.79012,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(1).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[1].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.04,
                 targetProbability, 4.79014,
                 1.0 / 1199892, 4.79012,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(2).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[2].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.87,
                 targetProbability, 4.79014,
                 1.0 / 1199892, 4.79012,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(3).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[3].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.73,
                 targetProbability, 4.79014,
                 1.0 / 1199892, 4.79012,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(4).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[4].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.59,
                 targetProbability, 4.79014,
                 1.0 / 1199833, 4.79011,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(5).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[5].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.35,
                 targetProbability, 4.79014,
                 1.0 / 1197264, 4.78968,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(6).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[6].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.83,
                 targetProbability, 4.79014,
                 1.0 / 1196906, 4.78962,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(7).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[7].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.00,
                 targetProbability, 4.79014,
                 1.0 / 1197264, 4.78968,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(8).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[8].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.20,
                 targetProbability, 4.79014,
                 1.0 / 1197324, 4.78969,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(9).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[9].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.41,
                 targetProbability, 4.79014,
                 1.0 / 1197324, 4.78969,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(10).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[10].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.50,
                 targetProbability, 4.79014,
                 1.0 / 1197622, 4.78974,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(11).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[11].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.57,
                 targetProbability, 4.79014,
                 1.0 / 1197145, 4.78966,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(12).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[12].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.63,
                 targetProbability, 4.79014,
                 1.0 / 1196608, 4.78957,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(13).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[13].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.68,
                 targetProbability, 4.79014,
                 1.0 / 1196549, 4.78956,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(14).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[14].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.17,
                 targetProbability, 4.79014,
                 1.0 / 1199713, 4.79009,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(15).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[15].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 11.13,
                 targetProbability, 4.79014,
                 1.0 / 201269, 4.79035,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(16).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[16].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 9.24,
                 targetProbability, 4.79014,
                 1.0 / 197742, 4.78976,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(17).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[17].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.34,
                 targetProbability, 4.79014,
                 1.0 / 199056, 4.78998,
@@ -806,227 +806,227 @@
             SetGrassCoverErosionOutwardsHydraulicBoundaryLocationWaveHeightOutputValues(demoAssessmentSection.GrassCoverErosionOutwards);
         }
 
-        private static void SetHydraulicBoundaryLocationDesignWaterLevelOutputValues(ICollection<HydraulicBoundaryLocation> locations)
+        private static void SetHydraulicBoundaryLocationDesignWaterLevelOutputValues(IList<HydraulicBoundaryLocation> locations)
         {
             const double targetProbability = 1.0 / 30000;
             GeneralResult<TopLevelSubMechanismIllustrationPoint> generalResult = null;
-            locations.ElementAt(0).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[0].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.78,
                 targetProbability, 3.98788,
                 1.0 / 29996, 3.98785,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(1).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[1].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.77,
                 targetProbability, 3.98787893,
                 1.0 / 29996, 3.98785,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(2).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[2].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.77,
                 targetProbability, 3.98788,
                 1.0 / 29996, 3.98785,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(3).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[3].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.77,
                 targetProbability, 3.98788,
                 1.0 / 29996, 3.98785,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(4).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[4].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.76865,
                 targetProbability, 3.98788,
                 1.0 / 29996, 3.98784,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(5).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[5].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.93,
                 targetProbability, 3.98788,
                 1.0 / 29995, 3.98784,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(6).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[6].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.93,
                 targetProbability, 3.98788,
                 1.0 / 29995, 3.98784,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(7).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[7].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.93,
                 targetProbability, 3.98788,
                 1.0 / 29995, 3.98784,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(8).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[8].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.93,
                 targetProbability, 3.98788,
                 1.0 / 29995, 3.98784,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(9).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[9].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.93,
                 targetProbability, 3.98788,
                 1.0 / 29995, 3.98784,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(10).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[10].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.93,
                 targetProbability, 3.98788,
                 1.0 / 29995, 3.98784,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(11).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[11].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.93,
                 targetProbability, 3.98788,
                 1.0 / 29995, 3.98784,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(12).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[12].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.93,
                 targetProbability, 3.98788,
                 1.0 / 29995, 3.98784,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(13).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[13].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.93,
                 targetProbability, 3.98788,
                 1.0 / 29995, 3.98784,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(14).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[14].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.93,
                 targetProbability, 3.98788,
                 1.0 / 29995, 3.98784,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(15).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[15].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.54,
                 targetProbability, 3.98788,
                 1.0 / 29996, 3.98785,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(16).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[16].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 5.86,
                 targetProbability, 3.98788,
                 1.0 / 29994, 3.98783,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(17).DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[17].DesignWaterLevelCalculation.Output = new HydraulicBoundaryLocationOutput(
                 6.00,
                 targetProbability, 3.98788,
                 1.0 / 29993, 3.98782,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
         }
 
-        private static void SetHydraulicBoundaryLocationWaveHeightOutputValues(ICollection<HydraulicBoundaryLocation> locations)
+        private static void SetHydraulicBoundaryLocationWaveHeightOutputValues(IList<HydraulicBoundaryLocation> locations)
         {
             const double targetProbability = 1.0 / 30000;
             GeneralResult<TopLevelSubMechanismIllustrationPoint> generalResult = null;
-            locations.ElementAt(0).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[0].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.13,
                 targetProbability, 3.98788,
                 1.0 / 29972, 3.98766,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(1).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[1].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.19,
                 targetProbability, 3.98788,
                 1.0 / 29962, 3.98770,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(2).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[2].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.02,
                 targetProbability, 3.98788,
                 1.0 / 29977, 3.98758,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(3).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[3].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.87,
                 targetProbability, 3.98788,
                 1.0 / 29963, 3.98759,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(4).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[4].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.73,
                 targetProbability, 3.98788,
                 1.0 / 29957, 3.98754,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(5).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[5].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 2.65,
                 targetProbability, 3.98788,
                 1.0 / 30022, 3.98805,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(6).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[6].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.04,
                 targetProbability, 3.98788,
                 1.0 / 30001, 3.98789,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(7).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[7].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.20,
                 targetProbability, 3.98788,
                 1.0 / 30000, 3.98788,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(8).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[8].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.35,
                 targetProbability, 3.98788,
                 1.0 / 29996, 3.98785,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(9).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[9].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.53,
                 targetProbability, 3.98788,
                 1.0 / 29999, 3.98787,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(10).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[10].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.62,
                 targetProbability, 3.98788,
                 1.0 / 29888, 3.98699,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(11).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[11].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.68,
                 targetProbability, 3.98788,
                 1.0 / 29890, 3.98701,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(12).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[12].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.73,
                 targetProbability, 3.98788,
                 1.0 / 29882, 3.98694,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(13).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[13].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.75,
                 targetProbability, 3.98788,
                 1.0 / 29902, 3.98710,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(14).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[14].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 3.30,
                 targetProbability, 3.98788,
                 1.0 / 30037, 3.98817,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(15).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[15].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 9.57,
                 targetProbability, 3.98788,
                 1.0 / 29999, 3.98787,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(16).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[16].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 8.02,
                 targetProbability, 3.98788,
                 1.0 / 30108, 3.98873,
                 CalculationConvergence.CalculatedConverged,
                 generalResult);
-            locations.ElementAt(17).WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
+            locations[17].WaveHeightCalculation.Output = new HydraulicBoundaryLocationOutput(
                 4.11,
                 targetProbability, 3.98788,
                 1.0 / 29929, 3.98732,
Index: Ringtoets/ClosingStructures/test/Ringtoets.ClosingStructures.Data.TestUtil.Test/ClosingStructurePermutationHelperTest.cs
===================================================================
diff -u -r1e5300a95a25677488384a87ac159288529f3751 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/ClosingStructures/test/Ringtoets.ClosingStructures.Data.TestUtil.Test/ClosingStructurePermutationHelperTest.cs	(.../ClosingStructurePermutationHelperTest.cs)	(revision 1e5300a95a25677488384a87ac159288529f3751)
+++ Ringtoets/ClosingStructures/test/Ringtoets.ClosingStructures.Data.TestUtil.Test/ClosingStructurePermutationHelperTest.cs	(.../ClosingStructurePermutationHelperTest.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -76,17 +76,17 @@
             AssertParameters(testCaseDatas, false, false, false);
         }
 
-        private static void AssertTestNames(ICollection<TestCaseData> testCaseDatas, string targetName, string testResultDescription)
+        private static void AssertTestNames(IEnumerable<TestCaseData> testCaseDatas, string targetName, string testResultDescription)
         {
             IEnumerable<string> testNames = testCaseDatas
                 .Select(tcd => tcd.TestName)
                 .ToList();
-            Assert.AreEqual(testCaseDatas.Count, testNames.Distinct().Count());
+            Assert.AreEqual(testCaseDatas.Count(), testNames.Distinct().Count());
             Assert.IsTrue(testNames.All(tn => tn.StartsWith($"{targetName}_")));
             Assert.IsTrue(testNames.All(tn => tn.EndsWith($"_{testResultDescription}")));
         }
 
-        private static void AssertParameters(ICollection<TestCaseData> testCaseDatas, bool idUnique, bool nameUnique, bool locationUnique)
+        private static void AssertParameters(IEnumerable<TestCaseData> testCaseDatas, bool idUnique, bool nameUnique, bool locationUnique)
         {
             var differentStructures = new List<ClosingStructure>();
             var referenceStructure = new TestClosingStructure();
@@ -96,7 +96,8 @@
                 .OfType<ClosingStructure>()
                 .ToList();
 
-            Assert.AreEqual(testCaseDatas.Count, structures.Count());
+            int expectedTestDataCount = testCaseDatas.Count();
+            Assert.AreEqual(expectedTestDataCount, structures.Count());
 
             if (idUnique)
             {
@@ -149,7 +150,7 @@
             differentStructures.Add(structures.Single(s => !s.InflowModelType.Equals(referenceStructure.InflowModelType)));
             differentStructures.Add(structures.Single(s => !s.ProbabilityOrFrequencyOpenStructureBeforeFlooding.Equals(referenceStructure.ProbabilityOrFrequencyOpenStructureBeforeFlooding)));
             differentStructures.Add(structures.Single(s => !s.StructureNormalOrientation.Equals(referenceStructure.StructureNormalOrientation)));
-            Assert.AreEqual(testCaseDatas.Count, differentStructures.Distinct().Count());
+            Assert.AreEqual(expectedTestDataCount, differentStructures.Distinct().Count());
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/Common/src/Ringtoets.Common.Data/Contribution/FailureMechanismContribution.cs
===================================================================
diff -u -rf432893149ee8f4e74d4c21f082974fb89916150 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/src/Ringtoets.Common.Data/Contribution/FailureMechanismContribution.cs	(.../FailureMechanismContribution.cs)	(revision f432893149ee8f4e74d4c21f082974fb89916150)
+++ Ringtoets/Common/src/Ringtoets.Common.Data/Contribution/FailureMechanismContribution.cs	(.../FailureMechanismContribution.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -37,7 +37,7 @@
     {
         private static readonly Range<double> normValidityRange = new Range<double>(1.0 / 1000000, 1.0 / 10);
 
-        private readonly ICollection<FailureMechanismContributionItem> distribution = new List<FailureMechanismContributionItem>();
+        private readonly List<FailureMechanismContributionItem> distribution = new List<FailureMechanismContributionItem>();
         private readonly OtherFailureMechanism otherFailureMechanism = new OtherFailureMechanism();
         private double lowerLimitNorm;
         private double signalingNorm;
Index: Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/DikeProfilesImporter.cs
===================================================================
diff -u -ra940166534b3dd6e778de2e7c8e7e5241f3d3381 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/DikeProfilesImporter.cs	(.../DikeProfilesImporter.cs)	(revision a940166534b3dd6e778de2e7c8e7e5241f3d3381)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/DikeProfilesImporter.cs	(.../DikeProfilesImporter.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -104,7 +104,7 @@
         }
 
         private static IEnumerable<DikeProfile> CreateDikeProfiles(IEnumerable<ProfileLocation> dikeProfileLocationCollection,
-                                                                   ICollection<DikeProfileData> dikeProfileDataCollection)
+                                                                   IEnumerable<DikeProfileData> dikeProfileDataCollection)
         {
             var dikeProfiles = new List<DikeProfile>();
             foreach (ProfileLocation dikeProfileLocation in dikeProfileLocationCollection)
Index: Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/FailureMechanismSectionsImporter.cs
===================================================================
diff -u -r0320ab3a413cb6a55e3f615d8c62706a48121588 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/FailureMechanismSectionsImporter.cs	(.../FailureMechanismSectionsImporter.cs)	(revision 0320ab3a413cb6a55e3f615d8c62706a48121588)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/FailureMechanismSectionsImporter.cs	(.../FailureMechanismSectionsImporter.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -77,7 +77,7 @@
             }
 
             NotifyProgress(Resources.FailureMechanismSectionsImporter_ProgressText_Validating_imported_sections, 2, 3);
-            ICollection<FailureMechanismSection> readFailureMechanismSections = readResults.Items;
+            IEnumerable<FailureMechanismSection> readFailureMechanismSections = readResults.Items;
             if (HasStartOrEndPointsTooFarFromReferenceLine(referenceLine, readFailureMechanismSections))
             {
                 LogCriticalFileReadError(Resources.FailureMechanismSectionsImporter_Import_Imported_sections_too_far_from_current_referenceline);
@@ -175,7 +175,7 @@
             Log.Error(errorMessage);
         }
 
-        private static bool HasStartOrEndPointsTooFarFromReferenceLine(ReferenceLine referenceLine, ICollection<FailureMechanismSection> mechanismSections)
+        private static bool HasStartOrEndPointsTooFarFromReferenceLine(ReferenceLine referenceLine, IEnumerable<FailureMechanismSection> mechanismSections)
         {
             foreach (FailureMechanismSection failureMechanismSection in mechanismSections)
             {
@@ -197,7 +197,7 @@
                 .Min(segment => segment.GetEuclideanDistanceToPoint(point));
         }
 
-        private static bool IsTotalLengthOfSectionsTooDifferentFromReferenceLineLength(ReferenceLine referenceLine, ICollection<FailureMechanismSection> mechanismSections)
+        private static bool IsTotalLengthOfSectionsTooDifferentFromReferenceLineLength(ReferenceLine referenceLine, IEnumerable<FailureMechanismSection> mechanismSections)
         {
             double totalSectionsLength = mechanismSections.Sum(s => GetSectionLength(s));
             double referenceLineLength = GetLengthOfLine(referenceLine.Points);
Index: Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/ForeshoreProfilesImporter.cs
===================================================================
diff -u -ra940166534b3dd6e778de2e7c8e7e5241f3d3381 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/ForeshoreProfilesImporter.cs	(.../ForeshoreProfilesImporter.cs)	(revision a940166534b3dd6e778de2e7c8e7e5241f3d3381)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/ForeshoreProfilesImporter.cs	(.../ForeshoreProfilesImporter.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -105,7 +105,7 @@
         }
 
         private static IEnumerable<ForeshoreProfile> CreateForeshoreProfiles(IEnumerable<ProfileLocation> dikeProfileLocationCollection,
-                                                                             ICollection<DikeProfileData> dikeProfileDataCollection)
+                                                                             IEnumerable<DikeProfileData> dikeProfileDataCollection)
         {
             var foreshoreProfiles = new List<ForeshoreProfile>();
             foreach (ProfileLocation dikeProfileLocation in dikeProfileLocationCollection)
Index: Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/ProfilesImporter.cs
===================================================================
diff -u -r00da0d2f72214f140bceff0eaae5f14172c587de -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/ProfilesImporter.cs	(.../ProfilesImporter.cs)	(revision 00da0d2f72214f140bceff0eaae5f14172c587de)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/ProfilesImporter.cs	(.../ProfilesImporter.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -244,7 +244,7 @@
         /// <item>The shapefile has an attribute whose type is incorrect.</item>
         /// <item>The read <see cref="ProfileLocation"/> is outside the reference line.</item>
         /// </list></exception>
-        private void AddNextProfileLocation(ProfileLocationReader profileLocationReader, ICollection<ProfileLocation> profileLocations)
+        private void AddNextProfileLocation(ProfileLocationReader profileLocationReader, Collection<ProfileLocation> profileLocations)
         {
             ProfileLocation profileLocation = profileLocationReader.GetNextProfileLocation();
             double distanceToReferenceLine = GetDistanceToReferenceLine(profileLocation.Point);
Index: Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/StructuresImporter.cs
===================================================================
diff -u -ra940166534b3dd6e778de2e7c8e7e5241f3d3381 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/StructuresImporter.cs	(.../StructuresImporter.cs)	(revision a940166534b3dd6e778de2e7c8e7e5241f3d3381)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/FileImporters/StructuresImporter.cs	(.../StructuresImporter.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -386,7 +386,7 @@
         /// <item>The shapefile misses a value for a required attribute.</item>
         /// <item>The shapefile has an attribute whose type is incorrect.</item>
         /// </list></exception>
-        private void AddNextStructureLocation(StructureLocationReader structureLocationReader, ICollection<StructureLocation> structureLocations)
+        private void AddNextStructureLocation(StructureLocationReader structureLocationReader, Collection<StructureLocation> structureLocations)
         {
             StructureLocation structureLocation = structureLocationReader.GetNextStructureLocation();
             double distanceToReferenceLine = GetDistanceToReferenceLine(structureLocation.Point);
Index: Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLines/ReferenceLineMetaImporter.cs
===================================================================
diff -u -r7c3fee822d908135cf99bb6cf2803982b257d409 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLines/ReferenceLineMetaImporter.cs	(.../ReferenceLineMetaImporter.cs)	(revision 7c3fee822d908135cf99bb6cf2803982b257d409)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLines/ReferenceLineMetaImporter.cs	(.../ReferenceLineMetaImporter.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -73,7 +73,7 @@
         /// </list></exception>
         public IEnumerable<ReferenceLineMeta> GetReferenceLineMetas()
         {
-            ICollection<ReferenceLineMeta> referenceLineMetas = ReferenceLinesMetaReader.ReadReferenceLinesMetas(shapeFilePath);
+            List<ReferenceLineMeta> referenceLineMetas = ReferenceLinesMetaReader.ReadReferenceLinesMetas(shapeFilePath);
 
             ValidateReferenceLineMetas(referenceLineMetas);
 
@@ -127,7 +127,7 @@
             }
         }
 
-        private void ValidateReferenceLineMetas(ICollection<ReferenceLineMeta> referenceLineMetas)
+        private void ValidateReferenceLineMetas(IEnumerable<ReferenceLineMeta> referenceLineMetas)
         {
             if (referenceLineMetas.Any(rlm => string.IsNullOrEmpty(rlm.AssessmentSectionId)))
             {
@@ -136,7 +136,7 @@
                 throw new CriticalFileValidationException(message);
             }
 
-            int referenceLineMetasCount = referenceLineMetas.Count;
+            int referenceLineMetasCount = referenceLineMetas.Count();
             int referenceLineMetasDistinctCount = referenceLineMetas.Select(rlm => rlm.AssessmentSectionId).Distinct().Count();
             if (referenceLineMetasCount != referenceLineMetasDistinctCount)
             {
Index: Ringtoets/Common/src/Ringtoets.Common.IO/Structures/ValidationResult.cs
===================================================================
diff -u -r6ef5e439a6d9f40ebd9926251945e0935fbbc314 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/src/Ringtoets.Common.IO/Structures/ValidationResult.cs	(.../ValidationResult.cs)	(revision 6ef5e439a6d9f40ebd9926251945e0935fbbc314)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/Structures/ValidationResult.cs	(.../ValidationResult.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -39,7 +39,7 @@
         /// <exception cref="ArgumentNullException">Thrown when <paramref name="errorMessages"/> is <c>null</c>.</exception>
         /// <exception cref="ArgumentException">Thrown when any message in <paramref name="errorMessages"/> is <c>null</c>, 
         /// empty or consists of whitespace.</exception>
-        public ValidationResult(ICollection<string> errorMessages)
+        public ValidationResult(IEnumerable<string> errorMessages)
         {
             if (errorMessages == null)
             {
@@ -50,7 +50,7 @@
                 throw new ArgumentException("Invalid error message string.");
             }
 
-            IsValid = errorMessages.Count < 1;
+            IsValid = !errorMessages.Any();
             this.errorMessages.AddRange(errorMessages);
         }
 
Index: Ringtoets/Common/src/Ringtoets.Common.IO/SurfaceLines/SurfaceLinesCsvImporter.cs
===================================================================
diff -u -r4d079c086f5fd38a3989f03fe79e3c95b842bcf6 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/src/Ringtoets.Common.IO/SurfaceLines/SurfaceLinesCsvImporter.cs	(.../SurfaceLinesCsvImporter.cs)	(revision 4d079c086f5fd38a3989f03fe79e3c95b842bcf6)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/SurfaceLines/SurfaceLinesCsvImporter.cs	(.../SurfaceLinesCsvImporter.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -155,7 +155,7 @@
         /// <returns>Returns a collection of mechanism specific surface lines.</returns>
         /// <exception cref="ImportedDataTransformException">Thrown when transforming a surface
         /// line with characteristic points failed.</exception>
-        private IEnumerable<T> GetTransformedSurfaceLines(ICollection<SurfaceLine> surfaceLines, ICollection<CharacteristicPoints> characteristicPointsCollection)
+        private IEnumerable<T> GetTransformedSurfaceLines(IEnumerable<SurfaceLine> surfaceLines, IEnumerable<CharacteristicPoints> characteristicPointsCollection)
         {
             LogMissingSurfaceLinesOrCharacteristicPoints(surfaceLines, characteristicPointsCollection);
             Tuple<SurfaceLine, CharacteristicPoints>[] surfaceLinesWithCharacteristicPoints = surfaceLines.Select(sl => Tuple.Create(sl, characteristicPointsCollection.FirstOrDefault(cp => cp.Name == sl.Name))).ToArray();
@@ -181,7 +181,7 @@
             }
         }
 
-        private void LogMissingSurfaceLinesOrCharacteristicPoints(ICollection<SurfaceLine> readSurfaceLines, ICollection<CharacteristicPoints> readCharacteristicPointsLocations)
+        private void LogMissingSurfaceLinesOrCharacteristicPoints(IEnumerable<SurfaceLine> readSurfaceLines, IEnumerable<CharacteristicPoints> readCharacteristicPointsLocations)
         {
             string[] surfaceLinesWithCharacteristicPoints = readSurfaceLines.Select(sl => sl.Name).Intersect(readCharacteristicPointsLocations.Select(cp => cp.Name)).ToArray();
             if (readCharacteristicPointsLocations.Any())
@@ -285,7 +285,7 @@
             }
         }
 
-        private bool IsSurfaceLineAlreadyDefined(ICollection<SurfaceLine> readSurfaceLineIdentifiers, SurfaceLine surfaceLine)
+        private bool IsSurfaceLineAlreadyDefined(IEnumerable<SurfaceLine> readSurfaceLineIdentifiers, SurfaceLine surfaceLine)
         {
             if (readSurfaceLineIdentifiers.Any(i => i.Name == surfaceLine.Name))
             {
@@ -419,7 +419,7 @@
         /// <param name="reader">The reader to read the <see cref="CharacteristicPoints"/> from.</param>
         /// <exception cref="CriticalFileReadException">Thrown when <paramref name="list"/> already contains a <see cref="CharacteristicPoints"/>
         /// with the same name as the new <see cref="CharacteristicPoints"/>.</exception>
-        private void AddValidCharacteristicPointsLocationToCollection(ICollection<CharacteristicPoints> list, CharacteristicPointsCsvReader reader)
+        private void AddValidCharacteristicPointsLocationToCollection(List<CharacteristicPoints> list, CharacteristicPointsCsvReader reader)
         {
             try
             {
Index: Ringtoets/Common/src/Ringtoets.Common.Service/RingtoetsCommonDataSynchronizationService.cs
===================================================================
diff -u -r8bb6e849266ec28412ebfe23beccd7235c4db9bf -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/src/Ringtoets.Common.Service/RingtoetsCommonDataSynchronizationService.cs	(.../RingtoetsCommonDataSynchronizationService.cs)	(revision 8bb6e849266ec28412ebfe23beccd7235c4db9bf)
+++ Ringtoets/Common/src/Ringtoets.Common.Service/RingtoetsCommonDataSynchronizationService.cs	(.../RingtoetsCommonDataSynchronizationService.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -142,7 +142,7 @@
                 .Where(c => ReferenceEquals(c.InputParameters.Structure, structure))
                 .ToArray();
 
-            ICollection<IObservable> changedObservables = ClearStructureDependentData(
+            List<IObservable> changedObservables = ClearStructureDependentData(
                 sectionResults,
                 calculationWithRemovedStructure,
                 calculations);
@@ -188,7 +188,7 @@
                 .Where(c => c.InputParameters.Structure != null)
                 .ToArray();
 
-            ICollection<IObservable> changedObservables = ClearStructureDependentData(
+            List<IObservable> changedObservables = ClearStructureDependentData(
                 sectionResults,
                 calculationWithRemovedStructure,
                 calculations);
@@ -199,7 +199,7 @@
             return changedObservables;
         }
 
-        private static ICollection<IObservable> ClearStructureDependentData<T>(IEnumerable<StructuresFailureMechanismSectionResult<T>> sectionResults,
+        private static List<IObservable> ClearStructureDependentData<T>(IEnumerable<StructuresFailureMechanismSectionResult<T>> sectionResults,
                                                                                IEnumerable<StructuresCalculation<T>> calculationWithRemovedStructure,
                                                                                IEnumerable<StructuresCalculation<T>> structureCalculations)
             where T : IStructuresCalculationInput<StructureBase>, new()
Index: Ringtoets/Common/test/Ringtoets.Common.Forms.Test/ChangeHandlers/FailureMechanismPropertyChangeHandlerTest.cs
===================================================================
diff -u -rac7c239fb7ae1c7cd0d0ab78957814df018d2242 -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/test/Ringtoets.Common.Forms.Test/ChangeHandlers/FailureMechanismPropertyChangeHandlerTest.cs	(.../FailureMechanismPropertyChangeHandlerTest.cs)	(revision ac7c239fb7ae1c7cd0d0ab78957814df018d2242)
+++ Ringtoets/Common/test/Ringtoets.Common.Forms.Test/ChangeHandlers/FailureMechanismPropertyChangeHandlerTest.cs	(.../FailureMechanismPropertyChangeHandlerTest.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -237,14 +237,14 @@
 
         public class ChangePropertyTestCase
         {
-            public ChangePropertyTestCase(ICollection<ICalculation> calculations)
+            public ChangePropertyTestCase(IEnumerable<ICalculation> calculations)
             {
                 Calculations = calculations;
                 ExpectedAffectedCalculations = calculations.Where(c => c.HasOutput).ToArray();
             }
 
-            public ICollection<ICalculation> Calculations { get; }
-            public ICollection<ICalculation> ExpectedAffectedCalculations { get; }
+            public IEnumerable<ICalculation> Calculations { get; }
+            public IEnumerable<ICalculation> ExpectedAffectedCalculations { get; }
         }
 
         private static IEnumerable ChangePropertyTestCases()
Index: Ringtoets/Common/test/Ringtoets.Common.IO.Test/FileImporters/HydraulicBoundaryDatabaseImporterTest.cs
===================================================================
diff -u -r6d901bde3aca6427d44fa379c8948594ecc8679a -r61c2ac2573d82151b0b1593260a419543d07122a
--- Ringtoets/Common/test/Ringtoets.Common.IO.Test/FileImporters/HydraulicBoundaryDatabaseImporterTest.cs	(.../HydraulicBoundaryDatabaseImporterTest.cs)	(revision 6d901bde3aca6427d44fa379c8948594ecc8679a)
+++ Ringtoets/Common/test/Ringtoets.Common.IO.Test/FileImporters/HydraulicBoundaryDatabaseImporterTest.cs	(.../HydraulicBoundaryDatabaseImporterTest.cs)	(revision 61c2ac2573d82151b0b1593260a419543d07122a)
@@ -262,7 +262,7 @@
             });
             Assert.IsTrue(importResult);
             Assert.IsFalse(assessmentSection.HydraulicBoundaryDatabase.CanUsePreprocessor);
-            ICollection<HydraulicBoundaryLocation> importedLocations = assessmentSection.HydraulicBoundaryDatabase.Locations;
+            List<HydraulicBoundaryLocation> importedLocations = assessmentSection.HydraulicBoundaryDatabase.Locations;
             Assert.AreEqual(9, importedLocations.Count);
             CollectionAssert.AllItemsAreNotNull(importedLocations);
             CollectionAssert.AllItemsAreUnique(importedLocations);
@@ -292,7 +292,7 @@
             // Assert
             Assert.IsTrue(importResult);
             Assert.AreEqual(copyValidFilePath, assessmentSection.HydraulicBoundaryDatabase.FilePath);
-            ICollection<HydraulicBoundaryLocation> importedLocations = assessmentSection.HydraulicBoundaryDatabase.Locations;
+            List<HydraulicBoundaryLocation> importedLocations = assessmentSection.HydraulicBoundaryDatabase.Locations;
             Assert.AreEqual(9, importedLocations.Count);
             CollectionAssert.AllItemsAreNotNull(importedLocations);
             CollectionAssert.AllItemsAreUnique(importedLocations);
@@ -321,7 +321,7 @@
             // Assert
             Assert.IsTrue(importResult);
             Assert.AreEqual(validFilePath, assessmentSection.HydraulicBoundaryDatabase.FilePath);
-            ICollection<HydraulicBoundaryLocation> importedLocations = assessmentSection.HydraulicBoundaryDatabase.Locations;
+            List<HydraulicBoundaryLocation> importedLocations = assessmentSection.HydraulicBoundaryDatabase.Locations;
             Assert.AreEqual(9, importedLocations.Count);
             CollectionAssert.AllItemsAreNotNull(importedLocations);
             CollectionAssert.AllItemsAreUnique(importedLocations);
@@ -357,7 +357,7 @@
             Assert.IsTrue(assessmentSection.HydraulicBoundaryDatabase.CanUsePreprocessor);
             Assert.IsTrue(assessmentSection.HydraulicBoundaryDatabase.UsePreprocessor);
             Assert.AreEqual(directory, assessmentSection.HydraulicBoundaryDatabase.PreprocessorDirectory);
-            ICollection<HydraulicBoundaryLocation> importedLocations = assessmentSection.HydraulicBoundaryDatabase.Locations;
+            List<HydraulicBoundaryLocation> importedLocations = assessmentSection.HydraulicBoundaryDatabase.Locations;
             Assert.AreEqual(106, importedLocations.Count);
             CollectionAssert.AllItemsAreNotNull(importedLocations);
             CollectionAssert.AllItemsAreUnique(importedLocations);
@@ -390,7 +390,7 @@
             });
             Assert.IsTrue(importResult);
             Assert.IsFalse(assessmentSection.HydraulicBoundaryDatabase.CanUsePreprocessor);
-            ICollection<HydraulicBoundaryLocation> importedLocations = assessmentSection.HydraulicBoundaryDatabase.Locations;
+            List<HydraulicBoundaryLocation> importedLocations = assessmentSection.HydraulicBoundaryDatabase.Locations;
             Assert.AreEqual(9, importedLocations.Count);
             CollectionAssert.AllItemsAreNotNull(importedLocations);
             CollectionAssert.AllItemsAreUnique(importedLocations);