void encodeHex(Text val, FsEntry entry, String field) {
   Object o = entry.get(field);
   if (o != null && o instanceof byte[]) {
     byte[] b = (byte[]) o;
     val.set(new String(Hex.encodeHex(b)));
   } else {
     LOG.warn(entry.fullPath() + " didn't have a hash for " + field);
     val.set("");
   }
 }