I am testing hibernate query with a simple filter where I want to select records based on whether a filter is being specified or not:

query = "select u from Unit u inner join u.rec rec where ( (:keywords is null) or rec.keyword.keyword in (:keywords) )"

I get this error when :keywords is NOT null:

org.springframework.orm.hibernate3.HibernateQueryException: unexpected AST node: {vector} [select u from com.zaztz.model.Unit u inner join u.rec rec where ( (:keywords0_, :keywords1_ is null) or rec.keyword.keyword in (:keywords0_, :keywords1_) )];

Is there any other function on params I can use that will check this properly?