@Override
    public AutoCloseable lock(Path path, Duration timeout) {
        return curator.lock(userRoot.append(path), timeout);
    }
Implementation of {@link VespaCurator} which delegates to a {@link Curator}.
This prefixes all paths with {@code "/user"}, to ensure separation with system ZK usage.

@author jonmv
zkfacade/src/main/java/com/yahoo/vespa/curator/CuratorWrapper.java