Moved models and removed deuplicate error for username since we use emails as username as well.

src/Api/Models/Request/FolderRequestModel.cs

@@ -0,0 +1,31 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+using Bit.Api.Utilities;
+using Bit.Core.Domains;
+
+namespace Bit.Api.Models
+{
+    public class FolderRequestModel
+    {
+        [Required]
+        [EncryptedString]
+        [StringLength(300)]
+        public string Name { get; set; }
+
+        public Folder ToFolder(string userId = null)
+        {
+            return new Folder
+            {
+                UserId = userId,
+                Name = Name
+            };
+        }
+
+        public Folder ToFolder(Folder existingFolder)
+        {
+            existingFolder.Name = Name;
+
+            return existingFolder;
+        }
+    }
+}