docs: public @Nonnull <T extends ResourceLoader> Optional<T> getLoader(@Nonnull Class<T> resolverType) {
          ArgumentUtils.requireNonNull("resolverType", resolverType);
          return resourceLoaders.stream()
              .filter(rl -> resolverType.isAssignableFrom(rl.getClass()))
              .map(rl -> (T) rl)
              .findFirst();
      }