Finally I found a mistake! Hope this is useful to someone. When doing a request to the database(in my case it Apache Derby), name of base need write the first letter upper case other in lower case.
This is wrong query:
session.createQuery("select first_name from CUSTOMERV").
This is valid query
session.createQuery("select first_name from Customerv").
And class entity must be same name as database, but I’m not sure.