code: synchronized void addResolvedPath(String path, F file) {
          _resolvedPaths.put(path, file);
          _unresolvedPaths.remove(path);
      }
docs: After each link is completely resolved, the linkTracker caller should
  call this method to store that resolved path so that it can be resolved
  directly the next time is is seen.
  
  @param path
  The path to the original symbolic link.
  @param file
  The file to which that link was finally resolved.