the setup program has the option to add the entry for the baseDN when doing an initial configuration
[root@ldap21 opendj]# ./setup --help
Usage: setup {options}
This utility can be used to setup the Directory Server
Command options:
-a, --addBaseEntry
Indicates whether to create the base entry in the Directory Server database
Similarly, control_panel has the option to Create Base Entry

However, there does not seem to be the same option when creating a backend or adding a baseDN with dsconfig, which means the entry for the baseDN must be added separately via an ldif
It would be good to have the same --addBaseEntry option in dsconfig that is found in setup