On my dates, there's a painfully long layover in ADD. But read this:
For passengers whose connecting flight is over 8 and up to 24 hours, interline desk will facilitate hotel accommodation provided that such passengers have transit /entry visa. For those nationals/ citizens who are eligible for transit visa on arrival, interline desk will facilitate such transit visa. The airline provides a bus service for transfer to/from hotel layover transit passengers.
It seems they pay for your visa if you are eligible for a visa on arrival (around USD 50 for EU citizens, if I remember correctly from May 2016).
Details:
https://www.ethiopianairlines.com/AA...baba-stopovers