diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestFeatures.pb.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestFeatures.pb.cs
index 048b09037b..beb8f16760 100644
--- a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestFeatures.pb.cs
+++ b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestFeatures.pb.cs
@@ -29,7 +29,7 @@ namespace Pb {
             "c3NhZ2UaTQoGTmVzdGVkMkMKC3Rlc3RfbmVzdGVkEhsuZ29vZ2xlLnByb3Rv",
             "YnVmLkZlYXR1cmVTZXQYjU4gASgLMhAucGIuVGVzdEZlYXR1cmVzMkQKDHRl",
             "c3RfbWVzc2FnZRIbLmdvb2dsZS5wcm90b2J1Zi5GZWF0dXJlU2V0GI5OIAEo",
-            "CzIQLnBiLlRlc3RGZWF0dXJlcyKXDAoMVGVzdEZlYXR1cmVzEnsKDGZpbGVf",
+            "CzIQLnBiLlRlc3RGZWF0dXJlcyLbCgoMVGVzdEZlYXR1cmVzEnsKDGZpbGVf",
             "ZmVhdHVyZRgBIAEoDjIPLnBiLkVudW1GZWF0dXJlQlSIAQGYAQGiAQsSBlZB",
             "TFVFMRiEB6IBCxIGVkFMVUUyGOcHogELEgZWQUxVRTMY6AeiAQwSBlZBTFVF",
             "NBidjQaiAQwSBlZBTFVFNRiejQayAQMI6AcSTAoXZXh0ZW5zaW9uX3Jhbmdl",
@@ -59,23 +59,19 @@ namespace Pb {
             "IOkHElQKDmZ1dHVyZV9mZWF0dXJlGBIgASgOMg8ucGIuRW51bUZlYXR1cmVC",
             "K4gBAZgBAZgBBKIBCxIGVkFMVUUxGIQHogELEgZWQUxVRTIY6QeyAQMI6QcS",
             "VwoObGVnYWN5X2ZlYXR1cmUYEyABKA4yDy5wYi5FbnVtRmVhdHVyZUIuiAEB",
-            "mAEBmAEEogELEgZWQUxVRTEYhAeiAQsSBlZBTFVFMhjoB7IBBgjmByDoBxJZ",
-            "Chlub19zdXBwb3J0X3dpbmRvd19mZWF0dXJlGBQgASgOMg8ucGIuRW51bUZl",
-            "YXR1cmVCJYgBAZgBAZgBBKIBCxIGVkFMVUUxGIQHogELEgZWQUxVRTIY6AcS",
-            "XwocZW1wdHlfc3VwcG9ydF93aW5kb3dfZmVhdHVyZRgVIAEoDjIPLnBiLkVu",
-            "dW1GZWF0dXJlQiiIAQGYAQGYAQSiAQsSBlZBTFVFMRiEB6IBCxIGVkFMVUUy",
-            "GOgHsgEAKuYBCgtFbnVtRmVhdHVyZRIdChlURVNUX0VOVU1fRkVBVFVSRV9V",
-            "TktOT1dOEAASCgoGVkFMVUUxEAESCgoGVkFMVUUyEAISCgoGVkFMVUUzEAMS",
-            "CgoGVkFMVUU0EAQSCgoGVkFMVUU1EAUSCgoGVkFMVUU2EAYSCgoGVkFMVUU3",
-            "EAcSCgoGVkFMVUU4EAgSCgoGVkFMVUU5EAkSCwoHVkFMVUUxMBAKEgsKB1ZB",
-            "TFVFMTEQCxILCgdWQUxVRTEyEAwSCwoHVkFMVUUxMxANEgsKB1ZBTFVFMTQQ",
-            "DhILCgdWQUxVRTE1EA86PAoEdGVzdBIbLmdvb2dsZS5wcm90b2J1Zi5GZWF0",
-            "dXJlU2V0GI9OIAEoCzIQLnBiLlRlc3RGZWF0dXJlcw=="));
+            "mAEBmAEEogELEgZWQUxVRTEYhAeiAQsSBlZBTFVFMhjoB7IBBgjmByDoByrm",
+            "AQoLRW51bUZlYXR1cmUSHQoZVEVTVF9FTlVNX0ZFQVRVUkVfVU5LTk9XThAA",
+            "EgoKBlZBTFVFMRABEgoKBlZBTFVFMhACEgoKBlZBTFVFMxADEgoKBlZBTFVF",
+            "NBAEEgoKBlZBTFVFNRAFEgoKBlZBTFVFNhAGEgoKBlZBTFVFNxAHEgoKBlZB",
+            "TFVFOBAIEgoKBlZBTFVFORAJEgsKB1ZBTFVFMTAQChILCgdWQUxVRTExEAsS",
+            "CwoHVkFMVUUxMhAMEgsKB1ZBTFVFMTMQDRILCgdWQUxVRTE0EA4SCwoHVkFM",
+            "VUUxNRAPOjwKBHRlc3QSGy5nb29nbGUucHJvdG9idWYuRmVhdHVyZVNldBiP",
+            "TiABKAsyEC5wYi5UZXN0RmVhdHVyZXM="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { global::Google.Protobuf.Reflection.DescriptorReflection.Descriptor, },
           new pbr::GeneratedClrTypeInfo(new[] {typeof(global::Pb.EnumFeature), }, new pb::Extension[] { UnittestFeaturesExtensions.Test }, new pbr::GeneratedClrTypeInfo[] {
             new pbr::GeneratedClrTypeInfo(typeof(global::Pb.TestMessage), global::Pb.TestMessage.Parser, null, null, null, new pb::Extension[] { global::Pb.TestMessage.Extensions.TestMessage }, new pbr::GeneratedClrTypeInfo[] { new pbr::GeneratedClrTypeInfo(typeof(global::Pb.TestMessage.Types.Nested), global::Pb.TestMessage.Types.Nested.Parser, null, null, null, new pb::Extension[] { global::Pb.TestMessage.Types.Nested.Extensions.TestNested }, null)}),
-            new pbr::GeneratedClrTypeInfo(typeof(global::Pb.TestFeatures), global::Pb.TestFeatures.Parser, new[]{ "FileFeature", "ExtensionRangeFeature", "MessageFeature", "FieldFeature", "OneofFeature", "EnumFeature", "EnumEntryFeature", "ServiceFeature", "MethodFeature", "MultipleFeature", "BoolFieldFeature", "SourceFeature", "SourceFeature2", "RemovedFeature", "FutureFeature", "LegacyFeature", "NoSupportWindowFeature", "EmptySupportWindowFeature" }, null, null, null, null)
+            new pbr::GeneratedClrTypeInfo(typeof(global::Pb.TestFeatures), global::Pb.TestFeatures.Parser, new[]{ "FileFeature", "ExtensionRangeFeature", "MessageFeature", "FieldFeature", "OneofFeature", "EnumFeature", "EnumEntryFeature", "ServiceFeature", "MethodFeature", "MultipleFeature", "BoolFieldFeature", "SourceFeature", "SourceFeature2", "RemovedFeature", "FutureFeature", "LegacyFeature" }, null, null, null, null)
           }));
     }
     #endregion
@@ -513,8 +509,6 @@ namespace Pb {
       removedFeature_ = other.removedFeature_;
       futureFeature_ = other.futureFeature_;
       legacyFeature_ = other.legacyFeature_;
-      noSupportWindowFeature_ = other.noSupportWindowFeature_;
-      emptySupportWindowFeature_ = other.emptySupportWindowFeature_;
       _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
     }
 
@@ -956,60 +950,6 @@ namespace Pb {
       _hasBits0 &= ~32768;
     }
 
-    /// <summary>Field number for the "no_support_window_feature" field.</summary>
-    public const int NoSupportWindowFeatureFieldNumber = 20;
-    private readonly static global::Pb.EnumFeature NoSupportWindowFeatureDefaultValue = global::Pb.EnumFeature.TestEnumFeatureUnknown;
-
-    private global::Pb.EnumFeature noSupportWindowFeature_;
-    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
-    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
-    public global::Pb.EnumFeature NoSupportWindowFeature {
-      get { if ((_hasBits0 & 65536) != 0) { return noSupportWindowFeature_; } else { return NoSupportWindowFeatureDefaultValue; } }
-      set {
-        _hasBits0 |= 65536;
-        noSupportWindowFeature_ = value;
-      }
-    }
-    /// <summary>Gets whether the "no_support_window_feature" field is set</summary>
-    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
-    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
-    public bool HasNoSupportWindowFeature {
-      get { return (_hasBits0 & 65536) != 0; }
-    }
-    /// <summary>Clears the value of the "no_support_window_feature" field</summary>
-    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
-    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
-    public void ClearNoSupportWindowFeature() {
-      _hasBits0 &= ~65536;
-    }
-
-    /// <summary>Field number for the "empty_support_window_feature" field.</summary>
-    public const int EmptySupportWindowFeatureFieldNumber = 21;
-    private readonly static global::Pb.EnumFeature EmptySupportWindowFeatureDefaultValue = global::Pb.EnumFeature.TestEnumFeatureUnknown;
-
-    private global::Pb.EnumFeature emptySupportWindowFeature_;
-    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
-    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
-    public global::Pb.EnumFeature EmptySupportWindowFeature {
-      get { if ((_hasBits0 & 131072) != 0) { return emptySupportWindowFeature_; } else { return EmptySupportWindowFeatureDefaultValue; } }
-      set {
-        _hasBits0 |= 131072;
-        emptySupportWindowFeature_ = value;
-      }
-    }
-    /// <summary>Gets whether the "empty_support_window_feature" field is set</summary>
-    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
-    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
-    public bool HasEmptySupportWindowFeature {
-      get { return (_hasBits0 & 131072) != 0; }
-    }
-    /// <summary>Clears the value of the "empty_support_window_feature" field</summary>
-    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
-    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
-    public void ClearEmptySupportWindowFeature() {
-      _hasBits0 &= ~131072;
-    }
-
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
     [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
     public override bool Equals(object other) {
@@ -1041,8 +981,6 @@ namespace Pb {
       if (RemovedFeature != other.RemovedFeature) return false;
       if (FutureFeature != other.FutureFeature) return false;
       if (LegacyFeature != other.LegacyFeature) return false;
-      if (NoSupportWindowFeature != other.NoSupportWindowFeature) return false;
-      if (EmptySupportWindowFeature != other.EmptySupportWindowFeature) return false;
       return Equals(_unknownFields, other._unknownFields);
     }
 
@@ -1066,8 +1004,6 @@ namespace Pb {
       if (HasRemovedFeature) hash ^= RemovedFeature.GetHashCode();
       if (HasFutureFeature) hash ^= FutureFeature.GetHashCode();
       if (HasLegacyFeature) hash ^= LegacyFeature.GetHashCode();
-      if (HasNoSupportWindowFeature) hash ^= NoSupportWindowFeature.GetHashCode();
-      if (HasEmptySupportWindowFeature) hash ^= EmptySupportWindowFeature.GetHashCode();
       if (_unknownFields != null) {
         hash ^= _unknownFields.GetHashCode();
       }
@@ -1150,14 +1086,6 @@ namespace Pb {
         output.WriteRawTag(152, 1);
         output.WriteEnum((int) LegacyFeature);
       }
-      if (HasNoSupportWindowFeature) {
-        output.WriteRawTag(160, 1);
-        output.WriteEnum((int) NoSupportWindowFeature);
-      }
-      if (HasEmptySupportWindowFeature) {
-        output.WriteRawTag(168, 1);
-        output.WriteEnum((int) EmptySupportWindowFeature);
-      }
       if (_unknownFields != null) {
         _unknownFields.WriteTo(output);
       }
@@ -1232,14 +1160,6 @@ namespace Pb {
         output.WriteRawTag(152, 1);
         output.WriteEnum((int) LegacyFeature);
       }
-      if (HasNoSupportWindowFeature) {
-        output.WriteRawTag(160, 1);
-        output.WriteEnum((int) NoSupportWindowFeature);
-      }
-      if (HasEmptySupportWindowFeature) {
-        output.WriteRawTag(168, 1);
-        output.WriteEnum((int) EmptySupportWindowFeature);
-      }
       if (_unknownFields != null) {
         _unknownFields.WriteTo(ref output);
       }
@@ -1298,12 +1218,6 @@ namespace Pb {
       if (HasLegacyFeature) {
         size += 2 + pb::CodedOutputStream.ComputeEnumSize((int) LegacyFeature);
       }
-      if (HasNoSupportWindowFeature) {
-        size += 2 + pb::CodedOutputStream.ComputeEnumSize((int) NoSupportWindowFeature);
-      }
-      if (HasEmptySupportWindowFeature) {
-        size += 2 + pb::CodedOutputStream.ComputeEnumSize((int) EmptySupportWindowFeature);
-      }
       if (_unknownFields != null) {
         size += _unknownFields.CalculateSize();
       }
@@ -1364,12 +1278,6 @@ namespace Pb {
       if (other.HasLegacyFeature) {
         LegacyFeature = other.LegacyFeature;
       }
-      if (other.HasNoSupportWindowFeature) {
-        NoSupportWindowFeature = other.NoSupportWindowFeature;
-      }
-      if (other.HasEmptySupportWindowFeature) {
-        EmptySupportWindowFeature = other.EmptySupportWindowFeature;
-      }
       _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
     }
 
@@ -1453,14 +1361,6 @@ namespace Pb {
             LegacyFeature = (global::Pb.EnumFeature) input.ReadEnum();
             break;
           }
-          case 160: {
-            NoSupportWindowFeature = (global::Pb.EnumFeature) input.ReadEnum();
-            break;
-          }
-          case 168: {
-            EmptySupportWindowFeature = (global::Pb.EnumFeature) input.ReadEnum();
-            break;
-          }
         }
       }
     #endif
@@ -1544,14 +1444,6 @@ namespace Pb {
             LegacyFeature = (global::Pb.EnumFeature) input.ReadEnum();
             break;
           }
-          case 160: {
-            NoSupportWindowFeature = (global::Pb.EnumFeature) input.ReadEnum();
-            break;
-          }
-          case 168: {
-            EmptySupportWindowFeature = (global::Pb.EnumFeature) input.ReadEnum();
-            break;
-          }
         }
       }
     }
diff --git a/csharp/src/Google.Protobuf.Test/testprotos.pb b/csharp/src/Google.Protobuf.Test/testprotos.pb
index 0f49934604..f42cf28db4 100644
Binary files a/csharp/src/Google.Protobuf.Test/testprotos.pb and b/csharp/src/Google.Protobuf.Test/testprotos.pb differ