Otherwise it does not register the "options" property and an assertion fails
when the user prints connection that has DHCPv6 options:

  $ LIBNM_GLIB_DEBUG=properties-changed nmcli c show yolo
  ...
  libnm-Message: Property 'options' unhandled.
  ...
  (process:13522): libnm-CRITICAL **: nm_dhcp_config_get_options: assertion 'NM_IS_DHCP_CONFIG (config)' failed