empty class data in class-update command causes assert in boost

command:

{"command": "class-update", "arguments": {"client-classes": [{}]})

casuses such assert in boost:

kea-dhcp4: /usr/include/boost/smart_ptr/shared_ptr.hpp:734: typename boost::detail::sp_member_access<T>::type boost::shared_ptr<T>::operator->() const [with T = const isc::data::Element; typename boost::detail::
sp_member_access<T>::type = const isc::data::Element*]: Assertion `px != 0' failed.