Adding swagger to asp.net web.api 2 owin

AuthTokenDocumentFilter.cs

public class AuthTokenDocumentFilter : IDocumentFilter
    {
        public void Apply(SwaggerDocument swaggerDoc, SchemaRegistry schemaRegistry, IApiExplorer apiExplorer)
        {
            swaggerDoc.paths.Add("/token", new PathItem
            {
                post = new Operation
                {
                    tags = new List<string> { "Auth" },
                    consumes = new List<string>
                {
                    "application/x-www-form-urlencoded"
                },
                    parameters = new List<Parameter> {
                    new Parameter
                    {
                        type = "string",
                        name = "grant_type",
                        required = true,
                        @in = "formData",
                        @default = "password"
                    },
                    new Parameter
                    {
                        type = "string",
                        name = "username",
                        required = false,
                        @in = "formData"
                    },
                    new Parameter
                    {
                        type = "string",
                        name = "password",
                        required = false,
                        @in = "formData"
                    }
                }
                }
            });
        }
    }

Startup.cs

 public class Startup
 {
        public void Configuration(IAppBuilder app)
        {
            var config = new HttpConfiguration();
            WebApiConfig.Register(config);
            app.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);

            SwaggerConfig.Register(config);
            app.UseWebApi(config);

        }
 }

SwaggerConfig.cs

public class SwaggerConfig
    {
        public static void Register(HttpConfiguration httpConfig)
        {
            var thisAssembly = typeof(SwaggerConfig).Assembly;

           httpConfig 
                .EnableSwagger(c =>
                    {
                        // API version definition
                        c.SingleApiVersion("v1", "AspNetWebAPIOauth2");

                        // Token 
                        c.ApiKey("Token")
                            .Description("Bearer token")
                            .Name("Authorization")
                            .In("header");

                        c.DocumentFilter<AuthTokenDocumentFilter>();
                    })
                .EnableSwaggerUi(c =>
                    {
                        // If your API supports ApiKey, you can override the default values.
                        // "apiKeyIn" can either be "query" or "header"                                                
                        //
                        c.EnableApiKeySupport("Authorization", "header");
                    });
        }
      }