GetRequiredSercie should not be nullable since the method throws an exception of service was not found

Author: Alexander-Ploskin

DevExpress.Mvvm.CodeGenerators.Tests/UnitTests/GenearationTests/GenerationTestsDx.cs

@@ -316,7 +316,7 @@ public object? ParentViewModel {
         protected IServiceContainer ServiceContainer { get => serviceContainer ??= new ServiceContainer(this); }
         IServiceContainer ISupportServices.ServiceContainer { get => ServiceContainer; }
         protected T? GetService<T>() where T : class => ServiceContainer.GetService<T>();
-        protected T? GetRequiredService<T>() where T : class => ServiceContainer.GetRequiredService<T>();
+        protected T GetRequiredService<T>() where T : class => ServiceContainer.GetRequiredService<T>();
 
         protected void RaisePropertyChanged(PropertyChangedEventArgs e) => PropertyChanged?.Invoke(this, e);
         protected void RaisePropertyChanging(PropertyChangingEventArgs e) => PropertyChanging?.Invoke(this, e);

DevExpress.Mvvm.CodeGenerators/Generators/InterfaceGenerator.cs

@@ -72,7 +72,7 @@ public void AppendImplementation(SourceBuilder source) {
             source.AppendIf(!isSealed, protectedModifier)
                   .AppendLine("T? GetService<T>() where T : class => ServiceContainer.GetService<T>();")
                   .AppendIf(!isSealed, protectedModifier)
-                  .AppendLine("T? GetRequiredService<T>() where T : class => ServiceContainer.GetRequiredService<T>();");
+                  .AppendLine("T GetRequiredService<T>() where T : class => ServiceContainer.GetRequiredService<T>();");
         }
     }
     class IActiveAwareGenerator : IInterfaceGenerator {