class JsonUtil {

  public static ObjectNode normalizeKeys(final ObjectNode objectNode) {
    final ObjectNode normalized = JsonUtil.createEmptyObjectNode();
    objectNode
        .fields()
        .forEachRemaining(
            entry -> {
              final String key = entry.getKey();
              final JsonNode value = entry.getValue();
              final String normalizedKey = key.toLowerCase(Locale.US);
              if (value instanceof ObjectNode) {
                normalized.set(normalizedKey, normalizeKeys((ObjectNode) value));
              } else {
                normalized.set(normalizedKey, value);
              }
            });
    return normalized;
  }

}