I cut the yak accidentally

Author: mgravell

Directory.Build.props

@@ -22,7 +22,7 @@
     <IncludeSymbols>false</IncludeSymbols>
     <IsTestProject>$(MSBuildProjectName.Contains('Test'))</IsTestProject>
     <Nullable>enable</Nullable>
-    <LangVersion>preview</LangVersion>
+    <LangVersion>8.0</LangVersion>
     <!--<CodeAnalysisRuleset>$(MSBuildThisFileDirectory)Shared.ruleset</CodeAnalysisRuleset>-->
 
     <ExampleRefs>local</ExampleRefs> <!-- local or nuget-->

examples/pb-net-grpc/Client_FS/Client_FS.fsproj

@@ -5,6 +5,7 @@
     <OutputType>Exe</OutputType>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <SignAssembly>false</SignAssembly>
+    <LangVersion>4.7</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>

examples/pb-net-grpc/Server_FS/Server_FS.fsproj

@@ -4,6 +4,7 @@
     <GenerateDocumentationFile>false</GenerateDocumentationFile>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <SignAssembly>false</SignAssembly>
+    <LangVersion>4.7</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>

examples/pb-net-grpc/Shared_FS/Shared_FS.fsproj

@@ -4,6 +4,7 @@
     <GenerateDocumentationFile>false</GenerateDocumentationFile>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <SignAssembly>false</SignAssembly>
+    <LangVersion>4.7</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>

src/protobuf-net.Grpc/Internal/ContractOperation.cs

@@ -316,12 +316,20 @@ where method.IsGenericMethodDefinition
             {(MethodType.Unary, ResultKind.Sync, VoidKind.Response), nameof(Reshape.UnarySyncVoid) },
         };
 #pragma warning restore CS0618
-        private string? GetClientHelperName() => Context switch
-        {
-            ContextKind.CallContext or ContextKind.NoContext or ContextKind.CancellationToken => _clientResponseMap.TryGetValue((MethodType, Result, Void & VoidKind.Response), out var helper) ? helper : null,
-            _ => null,
-        };
 
+        [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0066:Convert switch statement to expression", Justification = "Isn't actually C# 8.0 (but works on preview compiler)")]
+        private string? GetClientHelperName()
+        {
+            switch (Context)
+            {
+                case ContextKind.CallContext:
+                case ContextKind.NoContext:
+                case ContextKind.CancellationToken:
+                    return _clientResponseMap.TryGetValue((MethodType, Result, Void & VoidKind.Response), out var helper) ? helper : null;
+                default:
+                    return null;
+            };
+        }
 
         internal bool IsSyncT()
         {