private static @NotNull Collection<VirtualFile> getUnmergedFiles(@NotNull Project project,
                                                                   @NotNull Collection<? extends VirtualFile> roots) throws VcsException {
    Collection<VirtualFile> unmergedFiles = new HashSet<>();
    for (VirtualFile root : roots) {
      unmergedFiles.addAll(getUnmergedFiles(project, root));
    }
    return unmergedFiles;
  }
private static @NotNull Collection<VirtualFile> getUnmergedFiles(@NotNull Project project,
                                                                   @NotNull Collection<? extends VirtualFile> roots)