code: public Set<ClusterNode.GrantId> deleteAppFromNode(
        String nodeName, ResourceType type) {
      ClusterNode node = nameToNode.get(nodeName);
      if (node == null) {
        LOG.warn("Trying to delete type " + type +
          " from non-existent node: " + nodeName);
        return null;
      }
      return deleteAppFromNode(node, type);
    }
docs: Remove one application type from the node. Happens when the daemon
  responsible for handling this application type on the node goes down
  @param nodeName the name of the node
  @param type the type of the resource
  @return the list of grants that belonged to the application on this node