Grails does a good job of hiding the complexity of Java web-application programming, but it has to rely on some fairly elaborate mechanisms to do this. And, like any other lie, abstraction becomes more likely to unravel as it gets more complex. As The Bard tells us:
Truth will come to light; murder cannot be hid long; a man's son may, but in the end truth will out.A first encounter with the serialization requirement for objects in Grails webflow is like being a newlywed who has just unearthed a human femur while working in the garden. You have a choice. You can dig further to reveal the gruesome truth. Or you can shovel it over and try to set aside the possibility that your new beloved is an axe-murderer.
[1596 Shakespeare Merchant of Venice ii. ii. 73]