From 86728ecc17c339f699d21c8abd5ee93037b51a1e Mon Sep 17 00:00:00 2001
From: Ben Adams <thundercat@illyriad.co.uk>
Date: Wed, 1 May 2019 18:29:05 +0100
Subject: [PATCH] Seal some internal derived classes (#9880)

---
 src/Http/Headers/src/CookieHeaderParser.cs           |  7 +++----
 src/Http/Headers/src/ObjectCollection.cs             | 12 +-----------
 src/Http/Http.Abstractions/src/PathString.cs         |  2 +-
 src/Http/Http/src/Internal/ReferenceReadStream.cs    |  2 +-
 src/Http/WebUtilities/src/MultipartReaderStream.cs   |  2 +-
 .../Core/src/Adapter/Internal/LoggingStream.cs       |  2 +-
 .../Kestrel/Core/src/Adapter/Internal/RawStream.cs   |  2 +-
 src/Servers/Kestrel/Core/src/AnyIPListenOptions.cs   |  2 +-
 .../Kestrel/Core/src/Internal/ClosedStream.cs        |  2 +-
 .../Internal/Http/Http1ChunkedEncodingMessageBody.cs |  6 +++---
 .../Internal/Http/Http1ContentLengthMessageBody.cs   |  2 +-
 .../src/Internal/Http/Http1UpgradeMessageBody.cs     |  2 +-
 .../Core/src/Internal/Http/HttpRequestPipeReader.cs  |  2 +-
 .../Core/src/Internal/Http/HttpRequestStream.cs      |  2 +-
 .../Core/src/Internal/Http/HttpResponsePipeWriter.cs |  2 +-
 .../Core/src/Internal/Http/HttpResponseStream.cs     |  2 +-
 .../Core/src/Internal/Http/HttpUpgradeStream.cs      |  2 +-
 .../Internal/Http/ZeroContentLengthMessageBody.cs    |  2 +-
 .../Kestrel/Core/src/Internal/Http2/Bitshifter.cs    |  2 +-
 .../Internal/Http2/HPack/HPackDecodingException.cs   |  2 +-
 .../Internal/Http2/HPack/HPackEncodingException.cs   |  2 +-
 .../Internal/Http2/HPack/HuffmanDecodingException.cs |  2 +-
 .../Internal/Http2/Http2ConnectionErrorException.cs  |  2 +-
 .../Core/src/Internal/Http2/Http2MessageBody.cs      |  2 +-
 .../Http2SettingsParameterOutOfRangeException.cs     |  2 +-
 .../Core/src/Internal/Http2/Http2StreamContext.cs    |  2 +-
 .../src/Internal/Http2/Http2StreamErrorException.cs  |  2 +-
 .../Core/src/Internal/Http2/Http2StreamOfT.cs        |  2 +-
 .../ThrowingWasUpgradedWriteOnlyStream.cs            |  2 +-
 .../src/Internal/Infrastructure/WrappingStream.cs    |  2 +-
 .../Kestrel/Core/src/LocalhostListenOptions.cs       |  2 +-
 src/Shared/Buffers.MemoryPool/SlabMemoryPool.cs      |  2 +-
 32 files changed, 36 insertions(+), 47 deletions(-)

diff --git a/src/Http/Headers/src/CookieHeaderParser.cs b/src/Http/Headers/src/CookieHeaderParser.cs
index a94b61d319..7201ae21a1 100644
--- a/src/Http/Headers/src/CookieHeaderParser.cs
+++ b/src/Http/Headers/src/CookieHeaderParser.cs
@@ -6,14 +6,14 @@ using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.Net.Http.Headers
 {
-    internal class CookieHeaderParser : HttpHeaderParser<CookieHeaderValue>
+    internal sealed class CookieHeaderParser : HttpHeaderParser<CookieHeaderValue>
     {
         internal CookieHeaderParser(bool supportsMultipleValues)
             : base(supportsMultipleValues)
         {
         }
 
-        public sealed override bool TryParseValue(StringSegment value, ref int index, out CookieHeaderValue parsedValue)
+        public override bool TryParseValue(StringSegment value, ref int index, out CookieHeaderValue parsedValue)
         {
             parsedValue = null;
 
@@ -27,8 +27,7 @@ namespace Microsoft.Net.Http.Headers
                 return SupportsMultipleValues;
             }
 
-            var separatorFound = false;
-            var current = GetNextNonEmptyOrWhitespaceIndex(value, index, SupportsMultipleValues, out separatorFound);
+            var current = GetNextNonEmptyOrWhitespaceIndex(value, index, SupportsMultipleValues, out bool separatorFound);
 
             if (separatorFound && !SupportsMultipleValues)
             {
diff --git a/src/Http/Headers/src/ObjectCollection.cs b/src/Http/Headers/src/ObjectCollection.cs
index db5f876b53..f46b2dd743 100644
--- a/src/Http/Headers/src/ObjectCollection.cs
+++ b/src/Http/Headers/src/ObjectCollection.cs
@@ -11,7 +11,7 @@ namespace Microsoft.Net.Http.Headers
     // type to throw if 'null' gets added. Collection<T> internally uses List<T> which comes at some cost. In addition
     // Collection<T>.Add() calls List<T>.InsertItem() which is an O(n) operation (compared to O(1) for List<T>.Add()).
     // This type is only used for very small collections (1-2 items) to keep the impact of using Collection<T> small.
-    internal class ObjectCollection<T> : Collection<T>
+    internal sealed class ObjectCollection<T> : Collection<T>
     {
         internal static readonly Action<T> DefaultValidator = CheckNotNull;
         internal static readonly ObjectCollection<T> EmptyReadOnlyCollection
@@ -57,22 +57,12 @@ namespace Microsoft.Net.Http.Headers
 
         public bool IsReadOnly => ((ICollection<T>)this).IsReadOnly;
 
-        protected override void ClearItems()
-        {
-            base.ClearItems();
-        }
-
         protected override void InsertItem(int index, T item)
         {
             _validator(item);
             base.InsertItem(index, item);
         }
 
-        protected override void RemoveItem(int index)
-        {
-            base.RemoveItem(index);
-        }
-
         protected override void SetItem(int index, T item)
         {
             _validator(item);
diff --git a/src/Http/Http.Abstractions/src/PathString.cs b/src/Http/Http.Abstractions/src/PathString.cs
index 94b4da4101..8eba3914ca 100644
--- a/src/Http/Http.Abstractions/src/PathString.cs
+++ b/src/Http/Http.Abstractions/src/PathString.cs
@@ -472,7 +472,7 @@ namespace Microsoft.AspNetCore.Http
             => string.IsNullOrEmpty(s) ? new PathString(s) : FromUriComponent(s);
     }
 
-    internal class PathStringConverter : TypeConverter
+    internal sealed class PathStringConverter : TypeConverter
     {
         public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
             => sourceType == typeof(string) 
diff --git a/src/Http/Http/src/Internal/ReferenceReadStream.cs b/src/Http/Http/src/Internal/ReferenceReadStream.cs
index c36a59d010..2d14cc4311 100644
--- a/src/Http/Http/src/Internal/ReferenceReadStream.cs
+++ b/src/Http/Http/src/Internal/ReferenceReadStream.cs
@@ -11,7 +11,7 @@ namespace Microsoft.AspNetCore.Http.Internal
     /// <summary>
     /// A Stream that wraps another stream starting at a certain offset and reading for the given length.
     /// </summary>
-    internal class ReferenceReadStream : Stream
+    internal sealed class ReferenceReadStream : Stream
     {
         private readonly Stream _inner;
         private readonly long _innerOffset;
diff --git a/src/Http/WebUtilities/src/MultipartReaderStream.cs b/src/Http/WebUtilities/src/MultipartReaderStream.cs
index e1c4f642c8..e306fbfee0 100644
--- a/src/Http/WebUtilities/src/MultipartReaderStream.cs
+++ b/src/Http/WebUtilities/src/MultipartReaderStream.cs
@@ -10,7 +10,7 @@ using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.WebUtilities
 {
-    internal class MultipartReaderStream : Stream
+    internal sealed class MultipartReaderStream : Stream
     {
         private readonly MultipartBoundary _boundary;
         private readonly BufferedReadStream _innerStream;
diff --git a/src/Servers/Kestrel/Core/src/Adapter/Internal/LoggingStream.cs b/src/Servers/Kestrel/Core/src/Adapter/Internal/LoggingStream.cs
index d7d5e85590..dd54a32c2c 100644
--- a/src/Servers/Kestrel/Core/src/Adapter/Internal/LoggingStream.cs
+++ b/src/Servers/Kestrel/Core/src/Adapter/Internal/LoggingStream.cs
@@ -10,7 +10,7 @@ using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
 {
-    internal class LoggingStream : Stream
+    internal sealed class LoggingStream : Stream
     {
         private readonly Stream _inner;
         private readonly ILogger _logger;
diff --git a/src/Servers/Kestrel/Core/src/Adapter/Internal/RawStream.cs b/src/Servers/Kestrel/Core/src/Adapter/Internal/RawStream.cs
index 2875d0ad13..0258fc6c11 100644
--- a/src/Servers/Kestrel/Core/src/Adapter/Internal/RawStream.cs
+++ b/src/Servers/Kestrel/Core/src/Adapter/Internal/RawStream.cs
@@ -10,7 +10,7 @@ using System.Buffers;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
 {
-    internal class RawStream : Stream
+    internal sealed class RawStream : Stream
     {
         private readonly PipeReader _input;
         private readonly PipeWriter _output;
diff --git a/src/Servers/Kestrel/Core/src/AnyIPListenOptions.cs b/src/Servers/Kestrel/Core/src/AnyIPListenOptions.cs
index 2639337dd7..e2319b4977 100644
--- a/src/Servers/Kestrel/Core/src/AnyIPListenOptions.cs
+++ b/src/Servers/Kestrel/Core/src/AnyIPListenOptions.cs
@@ -10,7 +10,7 @@ using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core
 {
-    internal class AnyIPListenOptions : ListenOptions
+    internal sealed class AnyIPListenOptions : ListenOptions
     {
         internal AnyIPListenOptions(int port)
             : base(new IPEndPoint(IPAddress.IPv6Any, port))
diff --git a/src/Servers/Kestrel/Core/src/Internal/ClosedStream.cs b/src/Servers/Kestrel/Core/src/Internal/ClosedStream.cs
index a744faf0ec..15bd864bca 100644
--- a/src/Servers/Kestrel/Core/src/Internal/ClosedStream.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/ClosedStream.cs
@@ -8,7 +8,7 @@ using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Https.Internal
 {
-    internal class ClosedStream : Stream
+    internal sealed class ClosedStream : Stream
     {
         private static readonly Task<int> ZeroResultTask = Task.FromResult(result: 0);
 
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/Http1ChunkedEncodingMessageBody.cs b/src/Servers/Kestrel/Core/src/Internal/Http/Http1ChunkedEncodingMessageBody.cs
index 6de433251c..fdc8edb0cf 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/Http1ChunkedEncodingMessageBody.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/Http1ChunkedEncodingMessageBody.cs
@@ -16,7 +16,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
     /// <summary>
     ///   http://tools.ietf.org/html/rfc2616#section-3.6.1
     /// </summary>
-    internal class Http1ChunkedEncodingMessageBody : Http1MessageBody
+    internal sealed class Http1ChunkedEncodingMessageBody : Http1MessageBody
     {
         // byte consts don't have a data type annotation so we pre-cast it
         private const byte ByteCR = (byte)'\r';
@@ -209,7 +209,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             _requestBodyPipe.Reset();
         }
 
-        protected void Copy(ReadOnlySequence<byte> readableBuffer, PipeWriter writableBuffer)
+        private void Copy(ReadOnlySequence<byte> readableBuffer, PipeWriter writableBuffer)
         {
             if (readableBuffer.IsSingleSegment)
             {
@@ -229,7 +229,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             _pumpTask = PumpAsync();
         }
 
-        protected bool Read(ReadOnlySequence<byte> readableBuffer, PipeWriter writableBuffer, out SequencePosition consumed, out SequencePosition examined)
+        private bool Read(ReadOnlySequence<byte> readableBuffer, PipeWriter writableBuffer, out SequencePosition consumed, out SequencePosition examined)
         {
             consumed = default;
             examined = default;
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/Http1ContentLengthMessageBody.cs b/src/Servers/Kestrel/Core/src/Internal/Http/Http1ContentLengthMessageBody.cs
index dd2049d0ae..66d97819ba 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/Http1ContentLengthMessageBody.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/Http1ContentLengthMessageBody.cs
@@ -9,7 +9,7 @@ using Microsoft.AspNetCore.Connections;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
-    internal class Http1ContentLengthMessageBody : Http1MessageBody
+    internal sealed class Http1ContentLengthMessageBody : Http1MessageBody
     {
         private ReadResult _readResult;
         private readonly long _contentLength;
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/Http1UpgradeMessageBody.cs b/src/Servers/Kestrel/Core/src/Internal/Http/Http1UpgradeMessageBody.cs
index a197561698..3958fad0ba 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/Http1UpgradeMessageBody.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/Http1UpgradeMessageBody.cs
@@ -12,7 +12,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
     /// The upgrade stream uses the raw connection stream instead of going through the RequestBodyPipe. This
     /// removes the redundant copy from the transport pipe to the body pipe.
     /// </summary>
-    internal class Http1UpgradeMessageBody : Http1MessageBody
+    internal sealed class Http1UpgradeMessageBody : Http1MessageBody
     {
         public bool _completed;
         public Http1UpgradeMessageBody(Http1Connection context)
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestPipeReader.cs b/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestPipeReader.cs
index 02e5bf3648..17214ccb75 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestPipeReader.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestPipeReader.cs
@@ -13,7 +13,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
     /// <summary>
     /// Default HttpRequest PipeReader implementation to be used by Kestrel.
     /// </summary>
-    internal class HttpRequestPipeReader : PipeReader
+    internal sealed class HttpRequestPipeReader : PipeReader
     {
         private MessageBody _body;
         private HttpStreamState _state;
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestStream.cs b/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestStream.cs
index 587fdc55c0..10daf49dbb 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestStream.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestStream.cs
@@ -11,7 +11,7 @@ using Microsoft.AspNetCore.Http.Features;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
-    internal class HttpRequestStream : ReadOnlyPipeStream
+    internal sealed class HttpRequestStream : ReadOnlyPipeStream
     {
         private HttpRequestPipeReader _pipeReader;
         private readonly IHttpBodyControlFeature _bodyControl;
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/HttpResponsePipeWriter.cs b/src/Servers/Kestrel/Core/src/Internal/Http/HttpResponsePipeWriter.cs
index dc37670c61..a63fd9ebd9 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/HttpResponsePipeWriter.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/HttpResponsePipeWriter.cs
@@ -9,7 +9,7 @@ using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
-    internal class HttpResponsePipeWriter : PipeWriter
+    internal sealed class HttpResponsePipeWriter : PipeWriter
     {
         private HttpStreamState _state;
         private readonly IHttpResponseControl _pipeControl;
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/HttpResponseStream.cs b/src/Servers/Kestrel/Core/src/Internal/Http/HttpResponseStream.cs
index 0c9f19075e..2faed0e12f 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/HttpResponseStream.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/HttpResponseStream.cs
@@ -7,7 +7,7 @@ using Microsoft.AspNetCore.Http.Features;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
-    internal class HttpResponseStream : WriteOnlyPipeStream
+    internal sealed class HttpResponseStream : WriteOnlyPipeStream
     {
         private readonly HttpResponsePipeWriter _pipeWriter;
         private readonly IHttpBodyControlFeature _bodyControl;
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/HttpUpgradeStream.cs b/src/Servers/Kestrel/Core/src/Internal/Http/HttpUpgradeStream.cs
index 4557e6609d..cfa77d3eec 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/HttpUpgradeStream.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/HttpUpgradeStream.cs
@@ -8,7 +8,7 @@ using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
-    internal class HttpUpgradeStream : Stream
+    internal sealed class HttpUpgradeStream : Stream
     {
         private readonly Stream _requestStream;
         private readonly Stream _responseStream;
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/ZeroContentLengthMessageBody.cs b/src/Servers/Kestrel/Core/src/Internal/Http/ZeroContentLengthMessageBody.cs
index ab88b1e80e..d803271b89 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/ZeroContentLengthMessageBody.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/ZeroContentLengthMessageBody.cs
@@ -8,7 +8,7 @@ using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
-    internal class ZeroContentLengthMessageBody : MessageBody
+    internal sealed class ZeroContentLengthMessageBody : MessageBody
     {
         public ZeroContentLengthMessageBody(bool keepAlive)
             : base(null, null)
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http2/Bitshifter.cs b/src/Servers/Kestrel/Core/src/Internal/Http2/Bitshifter.cs
index 8aa5f59e35..2641343012 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http2/Bitshifter.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http2/Bitshifter.cs
@@ -9,7 +9,7 @@ using System.Runtime.CompilerServices;
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
 {
     // Mimics BinaryPrimitives with oddly sized units
-    internal class Bitshifter
+    internal static class Bitshifter
     {
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static uint ReadUInt24BigEndian(ReadOnlySpan<byte> source)
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HPackDecodingException.cs b/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HPackDecodingException.cs
index bb9d46aa25..d549554ab6 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HPackDecodingException.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HPackDecodingException.cs
@@ -5,7 +5,7 @@ using System;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.HPack
 {
-    internal class HPackDecodingException : Exception
+    internal sealed class HPackDecodingException : Exception
     {
         public HPackDecodingException(string message)
             : base(message)
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HPackEncodingException.cs b/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HPackEncodingException.cs
index d1ef84dc75..6911754476 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HPackEncodingException.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HPackEncodingException.cs
@@ -5,7 +5,7 @@ using System;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.HPack
 {
-    internal class HPackEncodingException : Exception
+    internal sealed class HPackEncodingException : Exception
     {
         public HPackEncodingException(string message)
             : base(message)
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HuffmanDecodingException.cs b/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HuffmanDecodingException.cs
index 43b324d94f..f20769f0b6 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HuffmanDecodingException.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http2/HPack/HuffmanDecodingException.cs
@@ -5,7 +5,7 @@ using System;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.HPack
 {
-    internal class HuffmanDecodingException : Exception
+    internal sealed class HuffmanDecodingException : Exception
     {
         public HuffmanDecodingException(string message)
             : base(message)
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2ConnectionErrorException.cs b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2ConnectionErrorException.cs
index 58556dd62c..4f06c98c2c 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2ConnectionErrorException.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2ConnectionErrorException.cs
@@ -5,7 +5,7 @@ using System;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
 {
-    internal class Http2ConnectionErrorException : Exception
+    internal sealed class Http2ConnectionErrorException : Exception
     {
         public Http2ConnectionErrorException(string message, Http2ErrorCode errorCode)
             : base($"HTTP/2 connection error ({errorCode}): {message}")
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2MessageBody.cs b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2MessageBody.cs
index e77b5c2fad..b2c8f7956d 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2MessageBody.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2MessageBody.cs
@@ -10,7 +10,7 @@ using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
 {
-    internal class Http2MessageBody : MessageBody
+    internal sealed class Http2MessageBody : MessageBody
     {
         private readonly Http2Stream _context;
         private ReadResult _readResult;
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2SettingsParameterOutOfRangeException.cs b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2SettingsParameterOutOfRangeException.cs
index 48cde17a80..05856cbf6e 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2SettingsParameterOutOfRangeException.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2SettingsParameterOutOfRangeException.cs
@@ -5,7 +5,7 @@ using System;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
 {
-    internal class Http2SettingsParameterOutOfRangeException : Exception
+    internal sealed class Http2SettingsParameterOutOfRangeException : Exception
     {
         public Http2SettingsParameterOutOfRangeException(Http2SettingsParameter parameter, long lowerBound, long upperBound)
             : base($"HTTP/2 SETTINGS parameter {parameter} must be set to a value between {lowerBound} and {upperBound}")
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamContext.cs b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamContext.cs
index 85646a2bfb..d3da32d373 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamContext.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamContext.cs
@@ -5,7 +5,7 @@ using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.FlowControl;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
 {
-    internal class Http2StreamContext : HttpConnectionContext
+    internal sealed class Http2StreamContext : HttpConnectionContext
     {
         public int StreamId { get; set; }
         public IHttp2StreamLifetimeHandler StreamLifetimeHandler { get; set; }
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamErrorException.cs b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamErrorException.cs
index c463111e69..532b300c81 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamErrorException.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamErrorException.cs
@@ -5,7 +5,7 @@ using System;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
 {
-    internal class Http2StreamErrorException : Exception
+    internal sealed class Http2StreamErrorException : Exception
     {
         public Http2StreamErrorException(int streamId, string message, Http2ErrorCode errorCode)
             : base($"HTTP/2 stream ID {streamId} error ({errorCode}): {message}")
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamOfT.cs b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamOfT.cs
index b408e27114..ee6bbd3d88 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamOfT.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2StreamOfT.cs
@@ -5,7 +5,7 @@ using Microsoft.AspNetCore.Hosting.Server;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
 {
-    internal class Http2Stream<TContext> : Http2Stream
+    internal sealed class Http2Stream<TContext> : Http2Stream
     {
         private readonly IHttpApplication<TContext> _application;
 
diff --git a/src/Servers/Kestrel/Core/src/Internal/Infrastructure/ThrowingWasUpgradedWriteOnlyStream.cs b/src/Servers/Kestrel/Core/src/Internal/Infrastructure/ThrowingWasUpgradedWriteOnlyStream.cs
index 78ead0c350..8036638f94 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Infrastructure/ThrowingWasUpgradedWriteOnlyStream.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Infrastructure/ThrowingWasUpgradedWriteOnlyStream.cs
@@ -8,7 +8,7 @@ using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure
 {
-    internal class ThrowingWasUpgradedWriteOnlyStream : WriteOnlyStream
+    internal sealed class ThrowingWasUpgradedWriteOnlyStream : WriteOnlyStream
     {
         public override bool CanSeek => false;
 
diff --git a/src/Servers/Kestrel/Core/src/Internal/Infrastructure/WrappingStream.cs b/src/Servers/Kestrel/Core/src/Internal/Infrastructure/WrappingStream.cs
index 6f1b13c39b..c62cda3342 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Infrastructure/WrappingStream.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Infrastructure/WrappingStream.cs
@@ -8,7 +8,7 @@ using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure
 {
-    internal class WrappingStream : Stream
+    internal sealed class WrappingStream : Stream
     {
         private Stream _inner;
         private bool _disposed;
diff --git a/src/Servers/Kestrel/Core/src/LocalhostListenOptions.cs b/src/Servers/Kestrel/Core/src/LocalhostListenOptions.cs
index ee28dce63e..80e008c78b 100644
--- a/src/Servers/Kestrel/Core/src/LocalhostListenOptions.cs
+++ b/src/Servers/Kestrel/Core/src/LocalhostListenOptions.cs
@@ -12,7 +12,7 @@ using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core
 {
-    internal class LocalhostListenOptions : ListenOptions
+    internal sealed class LocalhostListenOptions : ListenOptions
     {
         internal LocalhostListenOptions(int port)
             : base(new IPEndPoint(IPAddress.Loopback, port))
diff --git a/src/Shared/Buffers.MemoryPool/SlabMemoryPool.cs b/src/Shared/Buffers.MemoryPool/SlabMemoryPool.cs
index 2fa3a88d60..0359c72193 100644
--- a/src/Shared/Buffers.MemoryPool/SlabMemoryPool.cs
+++ b/src/Shared/Buffers.MemoryPool/SlabMemoryPool.cs
@@ -10,7 +10,7 @@ namespace System.Buffers
     /// <summary>
     /// Used to allocate and distribute re-usable blocks of memory.
     /// </summary>
-    internal class SlabMemoryPool : MemoryPool<byte>
+    internal sealed class SlabMemoryPool : MemoryPool<byte>
     {
         /// <summary>
         /// The size of a block. 4096 is chosen because most operating systems use 4k pages.