public boolean isDirty(
Object old,
Object current,
SessionImplementor session) throws HibernateException {
if ( isSame( old, current ) )

Object oldid = getIdentifier( old, session );
Object newid = getIdentifier( current, session );
return getIdentifierType( session ).isDirty( oldid, newid, session );
}

return getIdentifierType( session ).isDirty( oldid, newid, session );

==>

return getIdentifierOrUniqueKeyType( session ).isDirty( oldid, newid, session );