I am assuming the ClusterPage is not going to get more code and its only purpose is creation of EntityPage with right parameters. If this is so, then instead of adding new class can we add a method to EntityPage class:

pubic static EntityPage<Cluster> getClusterPage(WebDriver driver, PrismHelper helper, String entityName) {
    return new EntityPage(driver,helper,ENTITY_TYPE.CLUSTER,Cluster.class,entityName);
}

Same thing can be applicable for other class which only have a constructor and are not adding new behavior.