function defaultUpdater(session, action) {
    session.sessionBoundModels.forEach((modelClass) => {
        if (typeof modelClass.reducer === "function") {
            // This calls this.applyUpdate to update this.state
            modelClass.reducer(action, modelClass, session);
        }
    });
}
Calls all models' reducers if they exist.

@return {undefined}
@global