code: @Override
      public String getQuery() {
          if (elements.isEmpty()) {
              return "";
          }
          StringBuilder sb = new StringBuilder();
          if (elements.size() > 1) {
              sb.append("(&");
          }
          for (Entry<String, String> element : elements.entrySet()) {
              sb.append("(").append(element.getKey()).append("=").append(element.getValue()).append(")");
          }
          if (elements.size() > 1) {
              sb.append(")");
          }
          return sb.toString();
      }
docs: {@inheritDoc}