public ICollection <DependentRegistration> GetRegistrations(IEnumerable <Assembly> assemblies = null)
        {
            assemblies = assemblies ?? GetAssemblies()
                         .Where(a => a.GetCustomAttribute <DiscoverableAssemblyAttribute>() != null);

            var registrations = _dependentRegistrationFactory.CreateDependentRegistrations
                                (
                assemblies
                                );

            _registrationSorter.Sort(registrations);

            return(registrations);
        }