# Microsoft.Extensions.Configuration.CommandLine

``` diff
 namespace Microsoft.Extensions.Configuration.CommandLine {
     public class CommandLineConfigurationProvider : ConfigurationProvider {
-        public CommandLineConfigurationProvider(IEnumerable<string> args, IDictionary<string, string> switchMappings = null);
+        public CommandLineConfigurationProvider(IEnumerable<string> args, IDictionary<string, string>? switchMappings = null);
     }
     public class CommandLineConfigurationSource : IConfigurationSource {
-        public IDictionary<string, string> SwitchMappings { get; set; }
+        public IDictionary<string, string>? SwitchMappings { get; set; }
     }
 }
```

