Enable nullable for NuGet.Protocol Plugins runtime

src/NuGet.Core/NuGet.Protocol/Plugins/AutomaticProgressReporter.cs

@@ -1,8 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-#nullable disable
-
 using System;
 using System.Threading;
 using System.Threading.Tasks;
@@ -144,7 +142,7 @@ public static AutomaticProgressReporter Create(
                 cancellationToken);
         }
 
-        private void OnTimer(object state)
+        private void OnTimer(object? state)
         {
             try
             {

src/NuGet.Core/NuGet.Protocol/Plugins/Connection.cs

@@ -1,8 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-#nullable disable
-
 using System;
 using System.Threading;
 using System.Threading.Tasks;
@@ -30,12 +28,12 @@ public sealed class Connection : IConnection
         /// <summary>
         /// Occurs when an unrecoverable fault has been caught.
         /// </summary>
-        public event EventHandler<ProtocolErrorEventArgs> Faulted;
+        public event EventHandler<ProtocolErrorEventArgs>? Faulted;
 
         /// <summary>
         /// Occurs when a message has been received.
         /// </summary>
-        public event EventHandler<MessageEventArgs> MessageReceived;
+        public event EventHandler<MessageEventArgs>? MessageReceived;
 
         /// <summary>
         /// Gets the message dispatcher.
@@ -50,7 +48,7 @@ public sealed class Connection : IConnection
         /// <summary>
         /// Gets the negotiated protocol version, or <see langword="null" /> if not yet connected.
         /// </summary>
-        public SemanticVersion ProtocolVersion { get; private set; }
+        public SemanticVersion? ProtocolVersion { get; private set; }
 
         /// <summary>
         /// Instantiates a new instance of the <see cref="Connection" /> class.
@@ -271,7 +269,7 @@ public async Task SendAsync(Message message, CancellationToken cancellationToken
         /// <exception cref="OperationCanceledException">Thrown if <paramref name="cancellationToken" />
         /// is cancelled.</exception>
         /// <exception cref="InvalidOperationException">Thrown if not connected.</exception>
-        public Task<TInbound> SendRequestAndReceiveResponseAsync<TOutbound, TInbound>(
+        public Task<TInbound?> SendRequestAndReceiveResponseAsync<TOutbound, TInbound>(
             MessageMethod method,
             TOutbound payload,
             CancellationToken cancellationToken)
@@ -294,7 +292,7 @@ public Task<TInbound> SendRequestAndReceiveResponseAsync<TOutbound, TInbound>(
             return MessageDispatcher.DispatchRequestAsync<TOutbound, TInbound>(method, payload, cancellationToken);
         }
 
-        private void OnMessageReceived(object sender, MessageEventArgs e)
+        private void OnMessageReceived(object? sender, MessageEventArgs e)
         {
             if (_logger.IsEnabled)
             {
@@ -304,7 +302,7 @@ private void OnMessageReceived(object sender, MessageEventArgs e)
             MessageReceived?.Invoke(this, e);
         }
 
-        private void OnFaulted(object sender, ProtocolErrorEventArgs e)
+        private void OnFaulted(object? sender, ProtocolErrorEventArgs e)
         {
             Faulted?.Invoke(this, e);
         }

src/NuGet.Core/NuGet.Protocol/Plugins/IConnection.cs

@@ -16,12 +16,12 @@ public interface IConnection : IDisposable
         /// <summary>
         /// Occurs when an unrecoverable fault has been caught.
         /// </summary>
-        event EventHandler<ProtocolErrorEventArgs> Faulted;
+        event EventHandler<ProtocolErrorEventArgs>? Faulted;
 
         /// <summary>
         /// Occurs when a message has been received.
         /// </summary>
-        event EventHandler<MessageEventArgs> MessageReceived;
+        event EventHandler<MessageEventArgs>? MessageReceived;
 
         /// <summary>
         /// Gets the message dispatcher.
@@ -70,7 +70,7 @@ public interface IConnection : IDisposable
         /// <exception cref="OperationCanceledException">Thrown if <paramref name="cancellationToken" />
         /// is cancelled.</exception>
         /// <exception cref="InvalidOperationException">Thrown if not connected.</exception>
-        Task<TInbound> SendRequestAndReceiveResponseAsync<TOutbound, TInbound>(
+        Task<TInbound?> SendRequestAndReceiveResponseAsync<TOutbound, TInbound>(
             MessageMethod method,
             TOutbound payload,
             CancellationToken cancellationToken)

src/NuGet.Core/NuGet.Protocol/Plugins/IMessageDispatcher.cs

@@ -80,7 +80,7 @@ Message CreateMessage<TPayload>(MessageType type, MessageMethod method, TPayload
         /// <returns>A task that represents the asynchronous operation.
         /// The task result (<see cref="Task{TResult}.Result" />) returns a <typeparamref name="TInbound" />
         /// from the target.</returns>
-        Task<TInbound> DispatchRequestAsync<TOutbound, TInbound>(
+        Task<TInbound?> DispatchRequestAsync<TOutbound, TInbound>(
             MessageMethod method,
             TOutbound payload,
             CancellationToken cancellationToken)

src/NuGet.Core/NuGet.Protocol/Plugins/IPlugin.cs

@@ -13,12 +13,12 @@ public interface IPlugin : IDisposable
         /// <summary>
         /// Occurs before the plugin closes.
         /// </summary>
-        event EventHandler BeforeClose;
+        event EventHandler? BeforeClose;
 
         /// <summary>
         /// Occurs when the plugin has closed.
         /// </summary>
-        event EventHandler Closed;
+        event EventHandler? Closed;
 
         /// <summary>
         /// Gets the connection for the plugin.

src/NuGet.Core/NuGet.Protocol/Plugins/IPluginManager.cs

@@ -37,6 +37,6 @@ Task<IEnumerable<PluginCreationResult>> CreatePluginsAsync(
         /// <param name="pluginDiscoveryResult"></param>
         /// <param name="cancellationToken"></param>
         /// <returns>A PluginCreationResult</returns>
-        Task<Tuple<bool, PluginCreationResult>> TryGetSourceAgnosticPluginAsync(PluginDiscoveryResult pluginDiscoveryResult, OperationClaim requestedOperationClaim, CancellationToken cancellationToken);
+        Task<Tuple<bool, PluginCreationResult?>> TryGetSourceAgnosticPluginAsync(PluginDiscoveryResult pluginDiscoveryResult, OperationClaim requestedOperationClaim, CancellationToken cancellationToken);
     }
 }

src/NuGet.Core/NuGet.Protocol/Plugins/IReceiver.cs

@@ -13,12 +13,12 @@ public interface IReceiver : IDisposable
         /// <summary>
         /// Occurs when an unrecoverable fault has been caught.
         /// </summary>
-        event EventHandler<ProtocolErrorEventArgs> Faulted;
+        event EventHandler<ProtocolErrorEventArgs>? Faulted;
 
         /// <summary>
         /// Occurs when a message has been received.
         /// </summary>
-        event EventHandler<MessageEventArgs> MessageReceived;
+        event EventHandler<MessageEventArgs>? MessageReceived;
 
         /// <summary>
         /// Closes the connection.

src/NuGet.Core/NuGet.Protocol/Plugins/InboundRequestContext.cs

@@ -1,8 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-#nullable disable
-
 using System;
 using System.Threading;
 using System.Threading.Tasks;

src/NuGet.Core/NuGet.Protocol/Plugins/JsonSerializationUtilities.cs

@@ -1,8 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-#nullable disable
-
 using System;
 #if NET5_0_OR_GREATER
 using System.Diagnostics.CodeAnalysis;
@@ -48,14 +46,14 @@ static JsonSerializationUtilities()
         /// </summary>
         /// <typeparam name="T">The deserialization type.</typeparam>
         /// <param name="json">JSON to deserialize.</param>
-        /// <returns>An instance of <typeparamref name="T" />.</returns>
+        /// <returns>An instance of <typeparamref name="T" />, or <see langword="null" /> if the JSON represents a null value.</returns>
         /// <exception cref="ArgumentException">Thrown if <paramref name="json" />
         /// is either <see langword="null" /> or an empty string.</exception>
 #if NET5_0_OR_GREATER
         [RequiresUnreferencedCode("Uses Newtonsoft.Json reflection-based deserialization.")]
         [RequiresDynamicCode("Uses Newtonsoft.Json reflection-based deserialization.")]
 #endif
-        public static T Deserialize<T>(string json)
+        public static T? Deserialize<T>(string json)
             where T : class
         {
             if (string.IsNullOrEmpty(json))
@@ -115,13 +113,13 @@ public static void Serialize(JsonWriter writer, object value)
         /// </summary>
         /// <typeparam name="T">The deserialization type.</typeparam>
         /// <param name="jObject">A JSON object.</param>
-        /// <returns>An instance of <typeparamref name="T" />.</returns>
+        /// <returns>An instance of <typeparamref name="T" />, or <see langword="null" /> if the JSON represents a null value.</returns>
         /// <exception cref="ArgumentNullException">Thrown if <paramref name="jObject" /> is <see langword="null" />.</exception>
 #if NET5_0_OR_GREATER
         [RequiresUnreferencedCode("Uses Newtonsoft.Json reflection-based deserialization.")]
         [RequiresDynamicCode("Uses Newtonsoft.Json reflection-based deserialization.")]
 #endif
-        public static T ToObject<T>(JObject jObject)
+        public static T? ToObject<T>(JObject jObject)
         {
             if (jObject == null)
             {

src/NuGet.Core/NuGet.Protocol/Plugins/MessageDispatcher.cs

@@ -1,8 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-#nullable disable
-
 using System;
 using System.Collections.Concurrent;
 #if NET5_0_OR_GREATER
@@ -20,7 +18,7 @@ namespace NuGet.Protocol.Plugins
     /// </summary>
     public sealed class MessageDispatcher : IMessageDispatcher, IResponseHandler
     {
-        private IConnection _connection;
+        private IConnection? _connection;
         private readonly IIdGenerator _idGenerator;
         private bool _isClosed;
         private bool _isDisposed;
@@ -279,7 +277,7 @@ public Task DispatchProgressAsync(Message request, Progress progress, Cancellati
         /// from the target.</returns>
         /// <exception cref="OperationCanceledException">Thrown if <paramref name="cancellationToken" />
         /// is cancelled.</exception>
-        public Task<TInbound> DispatchRequestAsync<TOutbound, TInbound>(
+        public Task<TInbound?> DispatchRequestAsync<TOutbound, TInbound>(
             MessageMethod method,
             TOutbound payload,
             CancellationToken cancellationToken)
@@ -349,7 +347,7 @@ public Task DispatchResponseAsync<TOutbound>(
         /// Sets the connection to be used for dispatching messages.
         /// </summary>
         /// <param name="connection">A connection instance.  Can be <see langword="null" />.</param>
-        public void SetConnection(IConnection connection)
+        public void SetConnection(IConnection? connection)
         {
             if (_connection == connection)
             {
@@ -385,9 +383,7 @@ private async Task DispatchAsync<TOutgoing>(
             CancellationToken cancellationToken)
             where TOutgoing : class
         {
-            InboundRequestContext requestContext;
-
-            if (!_inboundRequestContexts.TryGetValue(request.RequestId, out requestContext))
+            if (!_inboundRequestContexts.TryGetValue(request.RequestId, out _))
             {
                 return;
             }
@@ -459,7 +455,7 @@ private async Task DispatchWithExistingContextAsync(
             await connection.SendAsync(response, cancellationToken);
         }
 
-        private async Task<TIncoming> DispatchWithNewContextAsync<TOutgoing, TIncoming>(
+        private async Task<TIncoming?> DispatchWithNewContextAsync<TOutgoing, TIncoming>(
             IConnection connection,
             MessageType type,
             MessageMethod method,
@@ -525,7 +521,7 @@ private async Task<TIncoming> DispatchWithNewContextAsync<TOutgoing, TIncoming>(
             return null;
         }
 
-        private void OnMessageReceived(object sender, MessageEventArgs e)
+        private void OnMessageReceived(object? sender, MessageEventArgs e)
         {
             // Capture _connection as SetConnection(...) could null it out later.
             var connection = _connection;
@@ -535,9 +531,7 @@ private void OnMessageReceived(object sender, MessageEventArgs e)
                 return;
             }
 
-            OutboundRequestContext requestContext;
-
-            if (_outboundRequestContexts.TryGetValue(e.Message.RequestId, out requestContext))
+            if (_outboundRequestContexts.TryGetValue(e.Message.RequestId, out var requestContext))
             {
                 switch (e.Message.Type)
                 {
@@ -593,9 +587,7 @@ private void OnMessageReceived(object sender, MessageEventArgs e)
 
         private void HandleInboundCancel(Message message)
         {
-            InboundRequestContext requestContext;
-
-            if (_inboundRequestContexts.TryGetValue(message.RequestId, out requestContext))
+            if (_inboundRequestContexts.TryGetValue(message.RequestId, out var requestContext))
             {
                 requestContext.Cancel();
             }
@@ -614,14 +606,14 @@ private void HandleInboundFault(Message fault)
 
             var payload = MessageUtilities.DeserializePayload<Fault>(fault);
 
-            throw new ProtocolException(payload.Message);
+            throw new ProtocolException(payload?.Message);
         }
 
         private void HandleInboundRequest(Message message)
         {
             var cancellationToken = CancellationToken.None;
-            IRequestHandler requestHandler = null;
-            ProtocolException exception = null;
+            IRequestHandler? requestHandler = null;
+            ProtocolException? exception = null;
 
             try
             {
@@ -643,15 +635,13 @@ private void HandleInboundRequest(Message message)
             }
             else
             {
-                requestContext.BeginFaultAsync(message, exception);
+                requestContext.BeginFaultAsync(message, exception!);
             }
         }
 
         private IRequestHandler GetInboundRequestHandler(MessageMethod method)
         {
-            IRequestHandler handler;
-
-            if (!RequestHandlers.TryGet(method, out handler))
+            if (!RequestHandlers.TryGet(method, out var handler))
             {
                 throw new ProtocolException(
                     string.Format(CultureInfo.CurrentCulture, Strings.Plugin_RequestHandlerDoesNotExist, method));
@@ -662,9 +652,7 @@ private IRequestHandler GetInboundRequestHandler(MessageMethod method)
 
         private OutboundRequestContext GetOutboundRequestContext(string requestId)
         {
-            OutboundRequestContext requestContext;
-
-            if (!_outboundRequestContexts.TryGetValue(requestId, out requestContext))
+            if (!_outboundRequestContexts.TryGetValue(requestId, out var requestContext))
             {
                 throw new ProtocolException(
                     string.Format(CultureInfo.CurrentCulture, Strings.Plugin_RequestContextDoesNotExist, requestId));
@@ -675,19 +663,15 @@ private OutboundRequestContext GetOutboundRequestContext(string requestId)
 
         private void RemoveInboundRequestContext(string requestId)
         {
-            InboundRequestContext requestContext;
-
-            if (_inboundRequestContexts.TryRemove(requestId, out requestContext))
+            if (_inboundRequestContexts.TryRemove(requestId, out var requestContext))
             {
                 requestContext.Dispose();
             }
         }
 
         private void RemoveOutboundRequestContext(string requestId)
         {
-            OutboundRequestContext requestContext;
-
-            if (_outboundRequestContexts.TryRemove(requestId, out requestContext))
+            if (_outboundRequestContexts.TryRemove(requestId, out var requestContext))
             {
                 requestContext.Dispose();
             }
@@ -698,7 +682,7 @@ private InboundRequestContext CreateInboundRequestContext(
             CancellationToken cancellationToken)
         {
             return new InboundRequestContext(
-                _connection,
+                _connection!,
                 message.RequestId,
                 cancellationToken,
                 _inboundRequestProcessingContext,
@@ -713,7 +697,7 @@ private OutboundRequestContext<TIncoming> CreateOutboundRequestContext<TIncoming
             where TIncoming : class
         {
             return new OutboundRequestContext<TIncoming>(
-                _connection,
+                _connection!,
                 message,
                 timeout,
                 isKeepAlive,

src/NuGet.Core/NuGet.Protocol/Plugins/Messages/GetOperationClaimsResponse.cs

@@ -1,8 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-#nullable disable
-
 using System;
 using System.Collections.Generic;
 using System.Globalization;

src/NuGet.Core/NuGet.Protocol/Plugins/Messages/HandshakeRequest.cs

@@ -1,8 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-#nullable disable
-
 using System;
 using System.Globalization;
 using Newtonsoft.Json;