docs: public static final String startToHex(ByteBuffer bb)
      {
          byte[] buf = new byte[bb.position()];
          int safePos = bb.position();
          int safeLim = bb.limit();
          bb.position(0);
          bb.get(buf);
          bb.position(safePos);
          bb.limit(safeLim);
          return toHex(buf);
      }