ReferenceError: Error #1056: Cannot create property handler

After updating my lcds application to LCSD 4.6  I get many of these errors. In debug log I can see, that java sends this handler property for some objects, e.g.

(com.mm_katalogy.model.MutaceStrankyDTO_$$_javassist_40){id=4} (1675022032) {

            id = 4

            nazev_stranky = 4

            seznam_oddeleni = [] (class: org.hibernate.collection.PersistentSet)

            fk_katalog_verze = 1

            handler = org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer@7f6714da

        }

But in my actionscript DTO objects there is no such property. How could I fix this?