The information is not clear. "Oil leak on the breather hose". Maybe a little more information.
Is the crankcase breather hose connected or slipped onto the hose barb or stub on the underside of the air box? The hose is routed down below and behind the engine. It's normal to have some minor oil accumulation in the air box and the hose directs any accumulated oil drippage onto the ground under the bike. If the hose is not connected any accumulation will fall onto the engine. There is a second hose connected to the bottom of the air box and it connects to the PAIR valve on the RH valve cover. If it is not slipped onto the hose stub on the air box it can also drip oil on the valve cover.