public static <T> T loadResource(String resourceName, Class<T> clazz) {
    try (var stream = YAML.class.getResourceAsStream(resourceName)) {
      return load(stream, clazz);
    } catch (IOException e) {
      throw new UncheckedIOException(e);
    }
  }
SnakeYaml doesn't handle the <a href="https://yaml.org/type/merge.html">merge operator</a> so manually post-process
the parsed yaml object to merge referenced objects into the parent one.
planetiler-core/src/main/java/com/onthegomap/planetiler/util/YAML.java