Hi. I did search the forum but found no answers, and I'm not sure it's a GXT or a GWT issue.

I have the following situation:

class CategoryModel extends BaseModel {}

class PersonModel extends BaseModel {
public void setCategory(CategoryModel c) {
set("category", c);

public CategoryModel getCategory() {
return get("category");

In my servlet I read "person" joinning it's "category", create the PersonModel, setting the CategoryModel property after that.

After the method ends, occurs a SerializarionException. The server log shows the following:

Caused by: com.google.gwt.user.client.rpc.SerializationException: Type 'br.unitoledo.base2.gwt.client.comum.models.CategoryModel' was not included in the set of types which can be serialized by this SerializationPolicy or its Class object could not be loaded. For security purposes, this type will not be serialized.: instance = br.unitoledo.base2.gwt.client.comum.models.CategoryModel@1b6a48d

The problem occurs only when I have nested ModelData insite another ModelData object. It doesn't work both ways (browser to servlet, servlet to browser).

Somebody having the same problem? Thanx in advance.