Update the Vkontakte provider to specify an explicit API version

Author: sla1k

src/AspNet.Security.OAuth.Vkontakte/VkontakteAuthenticationDefaults.cs

@@ -47,5 +47,10 @@ public static class VkontakteAuthenticationDefaults
         /// Default value for <see cref="OAuthOptions.UserInformationEndpoint"/>.
         /// </summary>
         public const string UserInformationEndpoint = "https://api.vk.com/method/users.get.json";
+
+        /// <summary>
+        /// Default API version.
+        /// </summary>
+        public const string ApiVersion = "5.78";
     }
 }

src/AspNet.Security.OAuth.Vkontakte/VkontakteAuthenticationHandler.cs

@@ -4,6 +4,7 @@
  * for more information concerning the license and the contributors participating to this project.
  */
 
+using System.Collections.Generic;
 using System.Net.Http;
 using System.Security.Claims;
 using System.Threading.Tasks;
@@ -27,7 +28,11 @@ public VkontakteAuthenticationHandler(HttpClient client)
 
         protected override async Task<AuthenticationTicket> CreateTicketAsync([NotNull] ClaimsIdentity identity, [NotNull] AuthenticationProperties properties, [NotNull] OAuthTokenResponse tokens)
         {
-            var address = QueryHelpers.AddQueryString(Options.UserInformationEndpoint, "access_token", tokens.AccessToken);
+            var address = QueryHelpers.AddQueryString(Options.UserInformationEndpoint, new Dictionary<string, string>
+            {
+                ["access_token"] = tokens.AccessToken,
+                ["v"] = !string.IsNullOrEmpty(Options.ApiVersion) ? Options.ApiVersion : VkontakteAuthenticationDefaults.ApiVersion
+            });
 
             if (Options.Fields.Count != 0)
             {

src/AspNet.Security.OAuth.Vkontakte/VkontakteAuthenticationHelper.cs

@@ -26,7 +26,7 @@ public static string GetId([NotNull] JObject user)
                 throw new ArgumentNullException(nameof(user));
             }
 
-            return user.Value<string>("uid");
+            return user.Value<string>("id");
         }
 
         /// <summary>

src/AspNet.Security.OAuth.Vkontakte/VkontakteAuthenticationOptions.cs

@@ -37,12 +37,18 @@ public VkontakteAuthenticationOptions()
         /// </summary>
         public ISet<string> Fields { get; } = new HashSet<string>
         {
-            "uid",
+            "id",
             "first_name",
             "last_name",
             "photo_rec",
             "photo",
             "hash"
         };
+
+        /// <summary>
+        /// Gets or sets the VKontakte API version.
+        /// See https://vk.com/dev/versions for more information.
+        /// </summary>
+        public string ApiVersion { get; set; } = VkontakteAuthenticationDefaults.ApiVersion;
     }
 }