restygwt/src/main/java/org/fusesource/restygwt/rebind/JsonEncoderDecoderClassCreator.java
private Collection<Type> findJsonSubTypes(JClassType clazz) {
        return findJsonSubTypes(clazz, new HashSet<JsonSubTypes.Type>());
    }
private Collection<Type> findJsonSubTypes(JClassType clazz) {
        return findJsonSubTypes(clazz, new HashSet<JsonSubTypes.Type>());
    }
This method does NOT return the subtypes of the given class, but all the subtypes associated with the
{@link JsonSubTypes} annotation, even if this annotation is assigned to
a parent class or an interface.