The ChildPrefixLength property was removed from the Partition Entity. Every TenantSupernetwork must now be configured with ChildPrefixLength accordingly.
This is done during startup in the database migration step and set to the same value as in the `Partition`.

It is required to add a defaultchildprefixlength property to the tenant super network in you configuration because otherwise the initial network creation will fail:
Sample:
  defaultchildprefixlength:
    IPv4: 22

Also ensure that all firewall-controllers are up-to-date in all firewalls before adding ipv6 prefixes to any of the exiting networks.