ClusterComunication.getInstance().removeDocument(this.getName(), docname);
ClusterComunication cluster = ClusterComunication.getInstance(); if(cluster!=null) cluster.removeDocument(this.getName(), docname);
    public void removeDocument(Txn transaction, DBBroker broker, String docname) throws PermissionDeniedException, TriggerException, LockException {        collection.removeDocument(transaction, broker, docname);        try {            ClusterComunication.getInstance().removeDocument(this.getName(), docname);        } catch (ClusterException e) {            e.printStackTrace();        }    }