Nhiberante map by code problem with UniqueKey("UQ_Name")

Property(x => x.RoomName, map => { map.Column(“RoomName”); map.UniqueKey(“UQ_RoomName”); map.NotNullable(true); map.Length(30); });

I’am using last version of Nhibernate VS SQL server 2016
when i try to may a unique key like this:

the name in database is never equal to my definicon “UQ_RoomName”

In the database i always see names like UQ__RoomName__5FC927668CB6A9E8

Can someone one help?