@Nullable
  @Override
  public UsageGroup getParentGroupFor(@NotNull Usage usage, UsageTarget @NotNull [] targets) {
    VirtualFile virtualFile;
    if (usage instanceof UsageInFile && (virtualFile = ((UsageInFile)usage).getFile()) != null) {
      return new FileUsageGroup(myProject, virtualFile);
    }
    return null;
  }
@Nullable
  @Override
  public UsageGroup getParentGroupFor(@NotNull Usage usage, UsageTarget @NotNull [] targets)