code: @Nullable
      protected <T> BeanRegistration<T> getActiveBeanRegistration(BeanDefinition<T> beanDefinition, Qualifier qualifier) {
          if (beanDefinition == null) {
              return null;
          }
          return singletonObjects.get(new BeanKey(beanDefinition, qualifier));
      }
docs: Find an active {@link javax.inject.Singleton} bean for the given definition and qualifier.
  
  @param beanDefinition The bean definition
  @param qualifier      The qualifier
  @param <T>            The bean generic type
  @return The bean registration