code: @SuppressWarnings("unchecked")
  	public static void setModelClass(Class<?> modelClass) throws IllegalArgumentException {
      	if (!DefaultModelImpl.class.isAssignableFrom(modelClass)) {
      		throw new IllegalArgumentException("Modelclass, " + modelClass.getName() + ", is not a subtype of " + DefaultModelImpl.class.getName());
      	}
  		ModelFactory.modelClass = (Class<DefaultModelImpl>)modelClass;
  	}
docs: Register a custom model class, must be a subclass to DefaultModelImpl.
  
  @param modelClass
  @throws IllegalArgumentException if supplied class is not a subclass of DefaultModelImpl