[Group 9] Enable nullable annotations for Microsoft.Extensions.Hosting.Systemd (#67513)

Fix #43605

* Annotate

* Fix API compat check by removing MemberNotNullWhen attribute.

Co-authored-by: Eric Erhardt <eric.erhardt@microsoft.com>

Author: maxkoshevoi

src/libraries/Microsoft.Extensions.Hosting.Systemd/ref/Microsoft.Extensions.Hosting.Systemd.csproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppMinimum);netstandard2.1</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <EnableDefaultItems>true</EnableDefaultItems>
   </PropertyGroup>
 

src/libraries/Microsoft.Extensions.Hosting.Systemd/src/Microsoft.Extensions.Hosting.Systemd.csproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppMinimum);netstandard2.1</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <EnableDefaultItems>true</EnableDefaultItems>
     <PackageDescription>.NET hosting infrastructure for Systemd Services.</PackageDescription>
     <!-- Use targeting pack references instead of granular ones in the project file. -->

src/libraries/Microsoft.Extensions.Hosting.Systemd/src/ServiceState.cs

@@ -26,9 +26,9 @@ public struct ServiceState
         /// <summary>
         /// Create custom ServiceState.
         /// </summary>
-        public ServiceState(string state)
+        public ServiceState(string state!!)
         {
-            _data = Encoding.UTF8.GetBytes(state ?? throw new ArgumentNullException(nameof(state)));
+            _data = Encoding.UTF8.GetBytes(state);
         }
 
         /// <summary>

src/libraries/Microsoft.Extensions.Hosting.Systemd/src/SystemdLifetime.cs

@@ -41,12 +41,12 @@ public Task WaitForStartAsync(CancellationToken cancellationToken)
         {
             _applicationStartedRegistration = ApplicationLifetime.ApplicationStarted.Register(state =>
             {
-                ((SystemdLifetime)state).OnApplicationStarted();
+                ((SystemdLifetime)state!).OnApplicationStarted();
             },
             this);
             _applicationStoppingRegistration = ApplicationLifetime.ApplicationStopping.Register(state =>
             {
-                ((SystemdLifetime)state).OnApplicationStopping();
+                ((SystemdLifetime)state!).OnApplicationStopping();
             },
             this);
 

src/libraries/Microsoft.Extensions.Hosting.Systemd/src/SystemdLifetime.netcoreapp.cs

@@ -8,7 +8,7 @@ namespace Microsoft.Extensions.Hosting.Systemd
 {
     public partial class SystemdLifetime
     {
-        private PosixSignalRegistration _sigTermRegistration;
+        private PosixSignalRegistration? _sigTermRegistration;
 
         private partial void RegisterShutdownHandlers()
         {

src/libraries/Microsoft.Extensions.Hosting.Systemd/src/SystemdNotifier.cs

@@ -12,14 +12,14 @@ public class SystemdNotifier : ISystemdNotifier
     {
         private const string NOTIFY_SOCKET = "NOTIFY_SOCKET";
 
-        private readonly string _socketPath;
+        private readonly string? _socketPath;
 
         public SystemdNotifier() :
             this(GetNotifySocketPath())
         { }
 
         // For testing
-        internal SystemdNotifier(string socketPath)
+        internal SystemdNotifier(string? socketPath)
         {
             _socketPath = socketPath;
         }
@@ -37,7 +37,7 @@ public void Notify(ServiceState state)
 
             using (var socket = new Socket(AddressFamily.Unix, SocketType.Dgram, ProtocolType.Unspecified))
             {
-                var endPoint = new UnixDomainSocketEndPoint(_socketPath);
+                var endPoint = new UnixDomainSocketEndPoint(_socketPath!);
                 socket.Connect(endPoint);
 
                 // It's safe to do a non-blocking call here: messages sent here are much
@@ -46,9 +46,9 @@ public void Notify(ServiceState state)
             }
         }
 
-        private static string GetNotifySocketPath()
+        private static string? GetNotifySocketPath()
         {
-            string socketPath = Environment.GetEnvironmentVariable(NOTIFY_SOCKET);
+            string? socketPath = Environment.GetEnvironmentVariable(NOTIFY_SOCKET);
 
             if (string.IsNullOrEmpty(socketPath))
             {