private @Nullable VcsRevisionNumber getLastRevision(@NotNull FilePath filePath, @Nullable VcsRevisionNumber currentRevision) {
    VcsKey gitKey = GitVcs.getKey();
    if (currentRevision != null) {
      VcsRevisionNumber cachedLastRevision = myCache.getLastRevision(filePath, gitKey, currentRevision);
      if (cachedLastRevision != null) {
        return cachedLastRevision;
      }
    }

    try {
      VcsRevisionNumber lastRevision = GitHistoryUtils.getCurrentRevision(myProject, filePath, GitUtil.HEAD);
      if (currentRevision != null && lastRevision != null) {
        myCache.putLastRevision(filePath, gitKey, currentRevision, lastRevision);
      }
      return lastRevision;
    }
    catch (VcsException e) {
      LOG.warn(e);
      return null;
    }
  }
private @Nullable VcsRevisionNumber getLastRevision(@NotNull FilePath filePath, @Nullable VcsRevisionNumber currentRevision)