private byte[] addVersion(VoteBlock block, String content) throws Exception {
   MessageDigest md = MessageDigest.getInstance("SHA1");
   md.update(content.getBytes());
   byte[] hash = md.digest();
   block.addVersion(0, content.length(), 0, content.length(), hash, hash, false);
   return hash;
 }
 private byte[] getHash(CachedUrlSet set, boolean namesOnly) throws IOException {
   MessageDigest dig = null;
   try {
     dig = MessageDigest.getInstance("SHA-1");
   } catch (NoSuchAlgorithmException ex) {
     fail("No algorithm.");
   }
   hash(set, dig, namesOnly);
   return dig.digest();
 }