Hi Tino (@flynux),
as I wrote above, your “raw” link gave me the correct file in size 
good to go. 
Installing and deinstalling 2.4.0 enocean binding doesn’t solve my issue, but I guess I have it run now. I tried several bindings from repo I might use in the future, already, e.g. avm for my fritzbox, network & WOL for general purpose, nothing did help up to now.
But since I own a Yamaha RX-S600D, I gave that feature a last chance directly after the last post. To my surprise, “feature:install openhab-transport-serial” made it thru without that dependency errors after “feature:install openhab-binding-yamahareceiver”. Quickly set up my eno bridge w/o hassle, it was up and running within seconds.
Therefor I guess all of you had already running bindings before using 2.5.0-SNAPSHOT and maybe nobody has ever tried to install it on a pristine installation, w/o other running bindings … looks like there is a little flaw in that jar … ?
Thanks and cheers.