In case this is design bug with Ext-GWT model objects I am posting an isolated description here.

Given the following two simple model objects

class ModelA extends BaseModel {
  setMembers(List<ModelB> members) {   ... }

class ModelB extends BaseModel {
A GWT service cannot return List<ModelA> , it fails during serialization by GWT claiming that that no serialization policy was defined for ModelB ???

If I make the model objects inherit from BaseTreeModel or Record the serilization works ok, but that's a poor solution.

I'm using GWT M2.

A somewhat more elaborate discussion on this is here: