URI dfsRoot = new URI(getDFSRootURL());
        String dfsRootPath = dfsRoot.getPath();
        int firstSep = dfsRootPath.indexOf('/', 1);
        String dfsShare;
        if ( firstSep > 0 ) {
            dfsShare = dfsRootPath.substring(1, firstSep);
        }
        else {
            dfsShare = dfsRootPath.substring(1, dfsRootPath.length() - 1);
        }
        return dfsShare;

        if ( prefixLen > 1 ) {
            prefixLen--;
            int firstSep = this.canon.indexOf('/', 1);
            if ( firstSep < 0 ) {
                this.share = this.canon.substring(1);
                this.unc = "\\";
            }
            else if ( firstSep == prefixLen ) {
                this.share = this.canon.substring(1, firstSep);
                this.unc = "\\";
            }
            else {

            Set<String> listLinks = new HashSet<>(Arrays.asList(list));
            int firstSep = link.indexOf('/');
            if ( firstSep == link.length() - 1 ) {
                // single level
                assertTrue("Link not found " + link, listLinks.contains(link));
            }
            else {
                link = link.substring(0, firstSep + 1);
                // single level

        long firstKey = prepareRequests(request, response, params, timeout);
        doSend(request);
        return firstKey;
    }


    /**
     * @param request
     * @param response
     * @param params
     * @param timeout
     * @param firstKey
     * @return
     * @throws IOException
     */

    assertThrows(NoSuchElementException.class, () -> navigableMap.firstKey());
  }

  @CollectionSize.Require(ZERO)
  public void testEmptyMapLast() {
    assertThrows(NoSuchElementException.class, () -> assertNull(navigableMap.lastKey()));
  }

  @CollectionSize.Require(ONE)
  public void testSingletonMapFirst() {
    assertEquals(a.getKey(), navigableMap.firstKey());
  }

  @CollectionSize.Require(ONE)

  @Override
  @CheckForNull
  public Comparator<? super K> comparator() {
    return delegate().comparator();
  }

  @Override
  @ParametricNullness
  public K firstKey() {
    return delegate().firstKey();
  }

  @Override
  public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
    return delegate().headMap(toKey);
  }

  @Override
  @ParametricNullness
  public K lastKey() {

    assertThrows(NoSuchElementException.class, () -> navigableMap.firstKey());
  }

  @CollectionSize.Require(ZERO)
  public void testEmptyMapLast() {
    assertThrows(NoSuchElementException.class, () -> assertNull(navigableMap.lastKey()));
  }

  @CollectionSize.Require(ONE)
  public void testSingletonMapFirst() {
    assertEquals(a.getKey(), navigableMap.firstKey());
  }

  @CollectionSize.Require(ONE)

  @Override
  @CheckForNull
  public Comparator<? super K> comparator() {
    return delegate().comparator();
  }

  @Override
  @ParametricNullness
  public K firstKey() {
    return delegate().firstKey();
  }

  @Override
  public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
    return delegate().headMap(toKey);
  }

  @Override
  @ParametricNullness
  public K lastKey() {

    }

    @Override
    @CheckForNull
    public Comparator<? super R> comparator() {
      return sortedBackingMap().comparator();
    }

    @Override
    public R firstKey() {
      return sortedBackingMap().firstKey();
    }

    @Override
    public R lastKey() {
      return sortedBackingMap().lastKey();
    }

    @Override
    public SortedMap<R, Map<C, V>> headMap(R toKey) {

    public Comparator<? super K> comparator() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate().comparator();
    }

    @Override
    public K firstKey() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate().firstKey();
    }

    @Override
    public K lastKey() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate().lastKey();
    }