@Override
    public Reader getHosts() {
        if (zkApplication.exists(Path.fromString(USERAPP_ZK_SUBPATH).append(HOSTS)))
        	return getUserAppData(HOSTS);
        return null;
    }
Reads allocated hosts at the given node.

@return the allocated hosts at this node or empty if there is no data at this path
configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackage.java