@NotNull
  public static <T> Map<VcsRoot, List<T>> groupByRoots(@NotNull Project project,
                                                       @NotNull Collection<? extends T> items,
                                                       @NotNull Function<? super T, ? extends FilePath> filePathMapper) {
    return groupByRoots(project, items, false, filePathMapper);
  }
@NotNull
  public static <T> Map<VcsRoot, List<T>> groupByRoots(@NotNull Project project,
                                                       @NotNull Collection<? extends T> items,
                                                       @NotNull Function<? super T, ? extends FilePath> filePathMapper)