@Override
  @Nullable
  public BackwardReferenceReader create(Project project) {
    File buildDir = BuildManager.getInstance().getProjectSystemDirectory(project);

    if (!CompilerReferenceIndex.exists(buildDir) || CompilerReferenceIndex.versionDiffers(buildDir, expectedIndexVersion())) {
      return null;
    }

    try {
      return new BackwardReferenceReader(project, buildDir, isCaseSensitiveFS(project));
    }
    catch (RuntimeException e) {
      LOG.error("An exception while initialization of compiler reference index.", e);
      return null;
    }
  }
@Override
  @Nullable
  public BackwardReferenceReader create(Project project)