Make RefreshToken method handle nullable requests

Updated the `RefreshToken` method to support nullable `request`
parameters, ensuring robustness when the request object is not
provided. Improved null safety by using the null-conditional
operator (`?.`) for accessing `RefreshToken`. Added logic to
create a new `RefreshTokenRequestDto` when `request` is null
and a cookie is available. Enhanced validation to prevent
potential `NullReferenceException` errors.

Author: Vadim Belov

Sources/EasyExtensions.AspNetCore.Authorization/Controllers/BaseAuthController.cs

@@ -71,18 +71,20 @@ public async Task<IActionResult> ChangePassword([FromBody] ChangePasswordRequest
         /// <returns>An <see cref="IActionResult"/> containing the new access token if the refresh token is valid; otherwise, a
         /// 404 Not Found result if the token is invalid or revoked.</returns>
         [HttpPost("refresh")]
-        public async Task<IActionResult> RefreshToken([FromBody] RefreshTokenRequestDto request)
+        public async Task<IActionResult> RefreshToken([FromBody] RefreshTokenRequestDto? request)
         {
-            bool useCookie = string.IsNullOrWhiteSpace(request.RefreshToken);
+            bool useCookie = string.IsNullOrWhiteSpace(request?.RefreshToken);
             if (useCookie)
             {
                 if (Request.Cookies.TryGetValue("refresh_token", out string? cookieRefreshToken))
                 {
-                    request = request with { RefreshToken = cookieRefreshToken };
+                    request = request is not null
+                        ? request with { RefreshToken = cookieRefreshToken }
+                        : new RefreshTokenRequestDto { RefreshToken = cookieRefreshToken };
                 }
             }
 
-            if (string.IsNullOrWhiteSpace(request.RefreshToken))
+            if (string.IsNullOrWhiteSpace(request?.RefreshToken))
             {
                 return this.ApiNotFound("Refresh token was not found");
             }

Sources/EasyExtensions.AspNetCore.Authorization/Models/Dto/RefreshTokenRequestDto.cs

@@ -1,6 +1,4 @@
-using System.ComponentModel.DataAnnotations;
-
-namespace EasyExtensions.AspNetCore.Authorization.Models.Dto
+namespace EasyExtensions.AspNetCore.Authorization.Models.Dto
 {
     /// <summary>
     /// Represents a request to refresh an authentication token using the current password.
@@ -10,7 +8,6 @@ public record RefreshTokenRequestDto
         /// <summary>
         /// Gets or sets the refresh token used to obtain a new access token when the current one expires.
         /// </summary>
-        [Required(AllowEmptyStrings = true)]
         public string? RefreshToken { get; set; }
     }
 }