/// <summary>
/// Extends the <see cref="IOptional{TContract}.Resolve" /> method by resolving the default dependency (without key).
/// </summary>
/// <typeparam name="TContract">The type of the dependency.</typeparam>
/// <param name="optional">The instance of <see cref="IOptional{TContract}" /> to extend.</param>
/// <returns>An instance of the dependency or null if not registered.</returns>
public static TContract Resolve <TContract>(this IOptional <TContract> optional) => optional.Resolve(null);
public OptionalTest(IOptional <IOptionalContract> optionalContract)
{
OptionalContract = optionalContract.Resolve();
}