public static IModuleBuilder<IWinApplicationBuilder> AddValidation(
    this IModuleBuilder<IWinApplicationBuilder> builder,
    Action<ValidationModuleOptions> configureOptions = null
)

<ExtensionAttribute>
Public Shared Function AddValidation(
    builder As IModuleBuilder(Of IWinApplicationBuilder),
    configureOptions As Action(Of ValidationModuleOptions) = Nothing
) As IModuleBuilder(Of IWinApplicationBuilder)

using DevExpress.ExpressApp.ApplicationBuilder;
using DevExpress.ExpressApp.Win.ApplicationBuilder;
// ...
public class ApplicationBuilder : IDesignTimeApplicationFactory {
    public static WinApplication BuildApplication(string connectionString) {
        var builder = WinApplication.CreateBuilder();
        builder.UseApplication<MySolutionWindowsFormsApplication>();
        builder.Modules
            // ...
            .AddValidation(options => {
                options.AllowValidationDetailsAccess = false;
                options.Events.OnCustomNeedToValidateRule += (context) => {
                    //...
                };
            })
        // ...
    }
    // ...
}