[Group 4] Enable nullable annotations for `Microsoft.Extensions.Logging.TraceSource` (#66892)

src/libraries/Microsoft.Extensions.Logging.TraceSource/ref/Microsoft.Extensions.Logging.TraceSource.cs

@@ -20,7 +20,7 @@ namespace Microsoft.Extensions.Logging.TraceSource
     public partial class TraceSourceLoggerProvider : Microsoft.Extensions.Logging.ILoggerProvider, System.IDisposable
     {
         public TraceSourceLoggerProvider(System.Diagnostics.SourceSwitch rootSourceSwitch) { }
-        public TraceSourceLoggerProvider(System.Diagnostics.SourceSwitch rootSourceSwitch, System.Diagnostics.TraceListener rootTraceListener) { }
+        public TraceSourceLoggerProvider(System.Diagnostics.SourceSwitch rootSourceSwitch, System.Diagnostics.TraceListener? rootTraceListener) { }
         public Microsoft.Extensions.Logging.ILogger CreateLogger(string name) { throw null; }
         public void Dispose() { }
     }

src/libraries/Microsoft.Extensions.Logging.TraceSource/ref/Microsoft.Extensions.Logging.TraceSource.csproj

 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>

src/libraries/Microsoft.Extensions.Logging.TraceSource/src/Microsoft.Extensions.Logging.TraceSource.csproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <EnableDefaultItems>true</EnableDefaultItems>
     <!-- Use targeting pack references instead of granular ones in the project file. -->
     <DisableImplicitAssemblyReferences>false</DisableImplicitAssemblyReferences>

src/libraries/Microsoft.Extensions.Logging.TraceSource/src/TraceSourceLogger.cs

@@ -16,7 +16,7 @@ public TraceSourceLogger(DiagnosticsTraceSource traceSource)
             _traceSource = traceSource;
         }
 
-        public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
+        public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
         {
             if (!IsEnabled(logLevel))
             {
@@ -36,7 +36,7 @@ public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Except
 
             if (exception != null)
             {
-                string exceptionDelimiter = string.IsNullOrEmpty(message) ? string.Empty : " " ;
+                string exceptionDelimiter = string.IsNullOrEmpty(message) ? string.Empty : " ";
                 message += exceptionDelimiter + exception;
             }
 
@@ -70,7 +70,7 @@ private static TraceEventType GetEventType(LogLevel logLevel)
             }
         }
 
-        public IDisposable BeginScope<TState>(TState state)
+        public IDisposable BeginScope<TState>(TState state) where TState : notnull
         {
             return new TraceSourceScope(state);
         }

src/libraries/Microsoft.Extensions.Logging.TraceSource/src/TraceSourceLoggerProvider.cs

@@ -15,7 +15,7 @@ namespace Microsoft.Extensions.Logging.TraceSource
     public class TraceSourceLoggerProvider : ILoggerProvider
     {
         private readonly SourceSwitch _rootSourceSwitch;
-        private readonly TraceListener _rootTraceListener;
+        private readonly TraceListener? _rootTraceListener;
 
         private readonly ConcurrentDictionary<string, DiagnosticsTraceSource> _sources = new ConcurrentDictionary<string, DiagnosticsTraceSource>(StringComparer.OrdinalIgnoreCase);
 
@@ -35,7 +35,7 @@ public TraceSourceLoggerProvider(SourceSwitch rootSourceSwitch)
         /// </summary>
         /// <param name="rootSourceSwitch">The <see cref="SourceSwitch"/> to use.</param>
         /// <param name="rootTraceListener">The <see cref="TraceListener"/> to use.</param>
-        public TraceSourceLoggerProvider(SourceSwitch rootSourceSwitch!!, TraceListener rootTraceListener)
+        public TraceSourceLoggerProvider(SourceSwitch rootSourceSwitch!!, TraceListener? rootTraceListener)
         {
             _rootSourceSwitch = rootSourceSwitch;
             _rootTraceListener = rootTraceListener;
@@ -59,7 +59,7 @@ private DiagnosticsTraceSource GetOrAddTraceSource(string name)
         private DiagnosticsTraceSource InitializeTraceSource(string traceSourceName)
         {
             var traceSource = new DiagnosticsTraceSource(traceSourceName);
-            string parentSourceName = ParentSourceName(traceSourceName);
+            string? parentSourceName = ParentSourceName(traceSourceName);
 
             if (string.IsNullOrEmpty(parentSourceName))
             {
@@ -92,7 +92,7 @@ private DiagnosticsTraceSource InitializeTraceSource(string traceSourceName)
             return traceSource;
         }
 
-        private static string ParentSourceName(string traceSourceName)
+        private static string? ParentSourceName(string traceSourceName)
         {
             int indexOfLastDot = traceSourceName.LastIndexOf('.');
             return indexOfLastDot == -1 ? null : traceSourceName.Substring(0, indexOfLastDot);