NetMQPoller implements ISynchronizeInvoke for all targets

This was previously only for NET40, but actually ISynchronizeInvoke is available in all supported target frameworks now, and there's no reason to exclude it in any of them.

Author: drewnoakes

src/NetMQ.Tests/NetMQPollerTest.cs

@@ -990,7 +990,6 @@ public async Task TwoThreads()
 
         #region ISynchronizeInvoke tests
 
-#if NET451
         [Fact]
         public void ISynchronizeInvokeWorks()
         {
@@ -1012,8 +1011,7 @@ public void ISynchronizeInvokeWorks()
                 Assert.True(isCorrectThread);
             }
         }
-#endif
 
-#endregion
+        #endregion
     }
 }

src/NetMQ/NetMQPoller.cs

@@ -1,12 +1,13 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Diagnostics;
 using System.Linq;
 using System.Net.Sockets;
 using System.Threading;
-using NetMQ.Core.Utils;
 using System.Threading.Tasks;
+using NetMQ.Core.Utils;
 
 using Switch = NetMQ.Core.Utils.Switch;
 
@@ -17,6 +18,7 @@ namespace NetMQ
     /// </summary>
     public sealed class NetMQPoller :
         TaskScheduler,
+        ISynchronizeInvoke,
 #pragma warning disable 618 // Type or member is obsolete
         INetMQPoller, ISocketPollableCollection, IEnumerable, IDisposable
 #pragma warning restore 618 // Type or member is obsolete
@@ -737,10 +739,9 @@ public void Dispose()
 
         #region ISynchronizeInvoke
 
-#if NET40
-        IAsyncResult ISynchronizeInvoke.BeginInvoke(Delegate method, object[] args)
+        IAsyncResult ISynchronizeInvoke.BeginInvoke(Delegate method, object?[]? args)
         {
-            var task = new Task<object>(() => method.DynamicInvoke(args));
+            var task = new Task<object?>(() => method.DynamicInvoke(args));
             task.Start(this);
             return task;
         }
@@ -751,18 +752,17 @@ object ISynchronizeInvoke.EndInvoke(IAsyncResult result)
             return task.Result;
         }
 
-        object ISynchronizeInvoke.Invoke(Delegate method, object[] args)
+        object? ISynchronizeInvoke.Invoke(Delegate method, object?[]? args)
         {
             if (CanExecuteTaskInline)
                 return method.DynamicInvoke(args);
 
-            var task = new Task<object>(() => method.DynamicInvoke(args));
+            var task = new Task<object?>(() => method.DynamicInvoke(args));
             task.Start(this);
             return task.Result;
         }
 
         bool ISynchronizeInvoke.InvokeRequired => !CanExecuteTaskInline;
-#endif
 
         #endregion
     }