migrate to the new CommandLineParser API

src/csharp/Grpc.IntegrationTesting/InteropClient.cs

@@ -56,24 +56,24 @@ namespace Grpc.IntegrationTesting
     {
         private class ClientOptions
         {
-            [Option("server_host", DefaultValue = "127.0.0.1")]
+            [Option("server_host", Default = "127.0.0.1")]
             public string ServerHost { get; set; }
 
-            [Option("server_host_override", DefaultValue = TestCredentials.DefaultHostOverride)]
+            [Option("server_host_override", Default = TestCredentials.DefaultHostOverride)]
             public string ServerHostOverride { get; set; }
 
             [Option("server_port", Required = true)]
             public int ServerPort { get; set; }
 
-            [Option("test_case", DefaultValue = "large_unary")]
+            [Option("test_case", Default = "large_unary")]
             public string TestCase { get; set; }
 
             // Deliberately using nullable bool type to allow --use_tls=true syntax (as opposed to --use_tls)
-            [Option("use_tls", DefaultValue = false)]
+            [Option("use_tls", Default = false)]
             public bool? UseTls { get; set; }
 
             // Deliberately using nullable bool type to allow --use_test_ca=true syntax (as opposed to --use_test_ca)
-            [Option("use_test_ca", DefaultValue = false)]
+            [Option("use_test_ca", Default = false)]
             public bool? UseTestCa { get; set; }
 
             [Option("default_service_account", Required = false)]

src/csharp/Grpc.IntegrationTesting/InteropServer.cs

@@ -51,11 +51,11 @@ namespace Grpc.IntegrationTesting
     {
         private class ServerOptions
         {
-            [Option("port", DefaultValue = 8070)]
+            [Option("port", Default = 8070)]
             public int Port { get; set; }
 
             // Deliberately using nullable bool type to allow --use_tls=true syntax (as opposed to --use_tls)
-            [Option("use_tls", DefaultValue = false)]
+            [Option("use_tls", Default = false)]
             public bool? UseTls { get; set; }
 
             [HelpOption]

src/csharp/Grpc.IntegrationTesting/QpsWorker.cs

@@ -52,7 +52,7 @@ namespace Grpc.IntegrationTesting
     {
         private class ServerOptions
         {
-            [Option("driver_port", DefaultValue = 0)]
+            [Option("driver_port", Default = 0)]
             public int DriverPort { get; set; }
 
             [HelpOption]

src/csharp/Grpc.IntegrationTesting/StressTestClient.cs

@@ -54,22 +54,22 @@ namespace Grpc.IntegrationTesting
 
         private class ClientOptions
         {
-            [Option("server_addresses", DefaultValue = "localhost:8080")]
+            [Option("server_addresses", Default = "localhost:8080")]
             public string ServerAddresses { get; set; }
 
-            [Option("test_cases", DefaultValue = "large_unary:100")]
+            [Option("test_cases", Default = "large_unary:100")]
             public string TestCases { get; set; }
 
-            [Option("test_duration_secs", DefaultValue = -1)]
+            [Option("test_duration_secs", Default = -1)]
             public int TestDurationSecs { get; set; }
 
-            [Option("num_channels_per_server", DefaultValue = 1)]
+            [Option("num_channels_per_server", Default = 1)]
             public int NumChannelsPerServer { get; set; }
 
-            [Option("num_stubs_per_channel", DefaultValue = 1)]
+            [Option("num_stubs_per_channel", Default = 1)]
             public int NumStubsPerChannel { get; set; }
 
-            [Option("metrics_port", DefaultValue = 8081)]
+            [Option("metrics_port", Default = 8081)]
             public int MetricsPort { get; set; }
 
             [HelpOption]