Grails / GORM apply criteria query with hasmany String for filter

I have a domain object (User) like this:

class User { String name static hasMany = [ permissions: String ] }

And I am trying to query all the User with certain permissions. So I have to join and check permissions property. Here how we can do this -

User.withCriteria { createAlias('permissions', 'n') ilike 'n.elements', '%permission_1%' }

The trick is to use 'n.elements'