@NotNull
  public static BackgroundableActionLock getHistorySessionLock(@NotNull AbstractVcs vcs,
                                                               @NotNull FilePath filePath,
                                                               @Nullable VcsRevisionNumber startRevisionNumber) {
    return getHistoryLock(vcs, VcsBackgroundableActions.CREATE_HISTORY_SESSION, filePath, startRevisionNumber);
  }
@NotNull
  public static BackgroundableActionLock getHistorySessionLock(@NotNull AbstractVcs vcs,
                                                               @NotNull FilePath filePath,
                                                               @Nullable VcsRevisionNumber startRevisionNumber)