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