NotNull
  protected Set<String> readItems() {
    try {
      InputStream resourceStream = resourceHolder.getResourceAsStream(relativePath);
      if (resourceStream == null) {
        throw new IOException("Resource " + relativePath + " not found");
      }
      try (BufferedReader reader = new BufferedReader(new InputStreamReader(resourceStream, StandardCharsets.UTF_8))) {
        final List<String> values = FileUtil.loadLines(reader);
        if (!values.isEmpty()) {
          return ContainerUtil.map2SetNotNull(values, s -> createValue(s));
        }
      }
    }
    catch (IOException e) {
      LOG.info(e);
    }
    return Collections.emptySet();
  }

NotNull
  protected Set<String> readItems() 