code: static String firstNonEmptyValue(String key, Map<?, ?>... maps) {
      for (Map<?, ?> map : maps) {
        String value = (String) map.get(key);
        if (!isEmpty(value)) {
          return value;
        }
      }
      return null;
    }
docs: Returns the first non-empty value mapped to the given key in the given maps, or null otherwise.