update Populate method to remove existing attributes only if it has name

SharpIpp/Protocol/Extensions/ListExtensions.cs

@@ -15,7 +15,7 @@ public static void Populate(this List<IppAttribute> list, IEnumerable<IppAttribu
 
             foreach (var additionalAttribute in other)
             {
-                list.RemoveAll(x => x.Name == additionalAttribute.Name);
+                list.RemoveAll(x => !string.IsNullOrEmpty(x.Name) && x.Name == additionalAttribute.Name);
                 list.Add(additionalAttribute);
             }
         }