docs: public static Map<String, AttributeValue> toAttributeValues(Item item) {
          if (item == null)
              return null;
          // row with multiple attributes
          Map<String, AttributeValue> result = new LinkedHashMap<String, AttributeValue>();
          for (Map.Entry<String, Object> entry : item.attributes())
              result.put(entry.getKey(), toAttributeValue(entry.getValue()));
          return result;
      }