private static @NotNull MessageDigest contentHashDigest() {
    // MAYBE: consider replace it with sha-256? It is 20%-30% slower than sha1, but more secure.
    //        For now I think this is not really a priority -- but we may consider the move at some point.

    //        Git has been used sha1 for years, and still uses it for legacy repos.
    //        If the question is about casual collisions probability, then sha1 is still good -- typically
    //        we have much less data in our content storage than a typical git-repository has, so it is
    //        likely we'll be fine with sha1 collisions probability.
    //        Malicious collisions are another topic: it is easier to generate a collision for sha1 than for
    //        sha256, but it is still quite expensive. And if the Evil is able to inject a carefully-crafted
    //        source file in my IDE source tree -- this itself is a huge security breach, because I could run
    //        a code from that file -- which seems much more dangerous than hash-collision.
    return DigestUtil.sha1();
  }
private static @NotNull MessageDigest contentHashDigest()