code: @Override
      public Object readValue(final Attribute _attribute,
                              final List<Object> _objectList)
      {
          Object ret = null;
          if (_objectList.size() < 1) {
              ret = null;
          } else if (_objectList.size() > 1) {
              final List<Long> list = new ArrayList<>();
              Long temp = null;
              for (final Object object : _objectList) {
                  if (object instanceof Number) {
                      temp = ((Number) object).longValue();
                  } else if (object != null) {
                      temp = Long.parseLong(object.toString());
                  }
                  list.add(object == null ? new Long(0) : temp);
              }
              ret = list;
          } else {
              final Object object = _objectList.get(0);
              Long temp = null;
              if (object instanceof Number) {
                  temp = ((Number) object).longValue();
              } else if (object != null) {
                  temp = Long.parseLong(object.toString());
              }
              ret = object == null ? new Long(0) : temp;
          }
          return ret;
      }
docs: {@inheritDoc}