Index: Core/Common/src/Core.Common.Util/FileFilterGenerator.cs
===================================================================
diff -u -r9e9976818f1b446948c3bf815cafe2e023f98ac1 -rf8b44e215e1c705f7284ba6c37ffd00b36641b1b
--- Core/Common/src/Core.Common.Util/FileFilterGenerator.cs	(.../FileFilterGenerator.cs)	(revision 9e9976818f1b446948c3bf815cafe2e023f98ac1)
+++ Core/Common/src/Core.Common.Util/FileFilterGenerator.cs	(.../FileFilterGenerator.cs)	(revision f8b44e215e1c705f7284ba6c37ffd00b36641b1b)
@@ -28,7 +28,7 @@
     /// Class which produces a file filter based on the expected extension. If no specific
     /// extension is expected, then a filter which filter out no file type will be produced.
     /// </summary>
-    public class FileFilterGenerator
+    public sealed class FileFilterGenerator
     {
         /// <summary>
         /// Creates a new instance of <see cref="FileFilterGenerator"/> which filters out no
Index: Core/Common/test/Core.Common.Util.Test/FileFilterGeneratorTest.cs
===================================================================
diff -u -r9e9976818f1b446948c3bf815cafe2e023f98ac1 -rf8b44e215e1c705f7284ba6c37ffd00b36641b1b
--- Core/Common/test/Core.Common.Util.Test/FileFilterGeneratorTest.cs	(.../FileFilterGeneratorTest.cs)	(revision 9e9976818f1b446948c3bf815cafe2e023f98ac1)
+++ Core/Common/test/Core.Common.Util.Test/FileFilterGeneratorTest.cs	(.../FileFilterGeneratorTest.cs)	(revision f8b44e215e1c705f7284ba6c37ffd00b36641b1b)
@@ -47,12 +47,12 @@
         public void Constructor_WithoutExtension_ThrowArgumentNullException(string extension)
         {
             // Call
-            TestDelegate test = () => new FileFilterGenerator(extension);
+            void Call() => new FileFilterGenerator(extension);
 
             // Assert
             const string expectedMessage = "Value required for the 'typeExtension'.";
             var exception = TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentException>(
-                test,
+                Call,
                 expectedMessage);
             Assert.AreEqual("typeExtension", exception.ParamName);
         }
@@ -63,12 +63,12 @@
         public void Constructor_WithoutExtensionWithDescription_ThrowArgumentException(string extension)
         {
             // Call
-            TestDelegate test = () => new FileFilterGenerator(extension, "description");
+            void Call() => new FileFilterGenerator(extension, "description");
 
             // Assert
             const string expectedMessage = "Value required for the 'typeExtension'.";
             var exception = TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentException>(
-                test,
+                Call,
                 expectedMessage);
             Assert.AreEqual("typeExtension", exception.ParamName);
         }
@@ -79,12 +79,12 @@
         public void Constructor_WithExtensionWithoutDescription_ThrowArgumentException(string description)
         {
             // Call
-            TestDelegate test = () => new FileFilterGenerator("txt", description);
+            void Call() => new FileFilterGenerator("txt", description);
 
             // Assert
             const string expectedMessage = "Value required for the 'typeDescription'.";
             var exception = TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentException>(
-                test,
+                Call,
                 expectedMessage);
             Assert.AreEqual("typeDescription", exception.ParamName);
         }
@@ -99,7 +99,7 @@
 
             // Assert
             Assert.AreEqual(extension, generator.Extension);
-            string description = $"{extension.ToUpperInvariant()}-bestanden";
+            var description = $"{extension.ToUpperInvariant()}-bestanden";
             Assert.AreEqual(description, generator.Description);
             Assert.AreEqual($"{description} (*.{extension})|*.{extension}", generator.Filter);
         }
@@ -119,18 +119,13 @@
         }
 
         [TestFixture]
-        private class FileFilterGeneratorEqualsTest : EqualsTestFixture<FileFilterGenerator, DerivedFileFilterGenerator>
+        private class FileFilterGeneratorEqualsTest : EqualsTestFixture<FileFilterGenerator>
         {
             protected override FileFilterGenerator CreateObject()
             {
                 return CreateFileFilterGenerator();
             }
 
-            protected override DerivedFileFilterGenerator CreateDerivedObject()
-            {
-                return new DerivedFileFilterGenerator(CreateFileFilterGenerator());
-            }
-
             private static IEnumerable<TestCaseData> GetUnequalTestCases()
             {
                 FileFilterGenerator baseGenerator = CreateFileFilterGenerator();
@@ -146,11 +141,5 @@
                 return new FileFilterGenerator("txt", "description");
             }
         }
-
-        private class DerivedFileFilterGenerator : FileFilterGenerator
-        {
-            public DerivedFileFilterGenerator(FileFilterGenerator generator)
-                : base(generator.Extension, generator.Description) {}
-        }
     }
 }
\ No newline at end of file