@Override
  protected @NotNull String getRollbackProposal() {
    Collection<GitRepository> repositories = getSuccessfulRepositories();
    String previousBranch = getIfSingle(repositories.stream().map(myCurrentHeads::get).distinct());
    if (previousBranch == null) previousBranch = GitBundle.message("checkout.operation.previous.branch");
    String rollBackProposal = GitBundle.message("checkout.operation.you.may.rollback.not.to.let.branches.diverge", previousBranch);
    return new HtmlBuilder()
      .append(GitBundle.message("checkout.operation.however.checkout.has.succeeded.for.the.following", repositories.size()))
      .br()
      .appendRaw(successfulRepositoriesJoined())
      .br()
      .append(rollBackProposal)
      .toString();
  }
@Override
  protected @NotNull String getRollbackProposal()