fix warnings in integration tests
diff --git a/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj b/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj
index db736ba..a1fb316 100755
--- a/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj
+++ b/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj
@@ -10,6 +10,7 @@
<PackageId>Grpc.IntegrationTesting.Server</PackageId>
<PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">$(PackageTargetFallback);portable-net45</PackageTargetFallback>
<RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
+ <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
</PropertyGroup>
<ItemGroup>