Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v3, actions/setup-dotnet@v3. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

The using directive for 'LangLang.Core.Controller' appeared previously in this namespace

The using directive for 'System' appeared previously in this namespace

The using directive for 'System.Collections.Generic' appeared previously in this namespace

The using directive for 'System.Linq' appeared previously in this namespace

The using directive for 'System.Text' appeared previously in this namespace

The using directive for 'System.Threading.Tasks' appeared previously in this namespace

The using directive for 'System.Windows' appeared previously in this namespace

'Course.ToString()' hides inherited member 'object.ToString()'. To make the current member override that implementation, add the override keyword. Otherwise add the new keyword.

Nullability of reference types in type of 'event PropertyChangedEventHandler TutorDTO.PropertyChanged' doesn't match implicitly implemented member 'event PropertyChangedEventHandler? INotifyPropertyChanged.PropertyChanged'.