@NotNull
 public SvnFileUrlMapping getSvnFileUrlMapping() {
   if (myMapping == null) {
     myMapping = SvnFileUrlMappingImpl.getInstance(myProject);
   }
   return myMapping;
 }
  @Override
  public <S> List<S> filterUniqueRoots(
      final List<S> in, final Convertor<S, VirtualFile> convertor) {
    if (in.size() <= 1) return in;

    final List<MyPair<S>> infos = new ArrayList<MyPair<S>>(in.size());
    final SvnFileUrlMappingImpl mapping = (SvnFileUrlMappingImpl) getSvnFileUrlMapping();
    final List<S> notMatched = new LinkedList<S>();
    for (S s : in) {
      final VirtualFile vf = convertor.convert(s);
      if (vf == null) continue;

      final File ioFile = new File(vf.getPath());
      SVNURL url = mapping.getUrlForFile(ioFile);
      if (url == null) {
        url = SvnUtil.getUrl(this, ioFile);
        if (url == null) {
          notMatched.add(s);
          continue;
        }
      }
      infos.add(new MyPair<S>(vf, url.toString(), s));
    }
    final List<MyPair<S>> filtered = new ArrayList<MyPair<S>>(infos.size());
    ForNestedRootChecker.filterOutSuperfluousChildren(this, infos, filtered);

    final List<S> converted =
        ObjectsConvertor.convert(
            filtered,
            new Convertor<MyPair<S>, S>() {
              @Override
              public S convert(final MyPair<S> o) {
                return o.getSrc();
              }
            });
    if (!notMatched.isEmpty()) {
      // potential bug is here: order is not kept. but seems it only occurs for cases where result
      // is sorted after filtering so ok
      converted.addAll(notMatched);
    }
    return converted;
  }