code: @Override
      public <T> List<T> getServices(final Class<T> serviceType) {
          @SuppressWarnings("unchecked")
          List<T> found = (List<T>) servicesLoaded.get(serviceType);
          if (found != null) {
              return found;
          }
  
          return loadServices(serviceType);
      }
docs: Loads and registers services.
  
  @param serviceType The service type.
  @param <T>         the concrete type.
  @return the items found, never {@code null}.