In case it is not a problem for you to put openhab’s password into a file you may try this ( Openhab-cli console +cron - #2 by Wolfgang_S ). Put the command into a shell script/file and call the file by running executeCommandLine.
In case you would like to run it using ssh public/private key pair: did you add the public key into openhab ssh configurationfile file which is: /var/lib/openhab/etc/keys.properties