code: private void addExtraHeaders(final ByteBuffer bb,
      final Object... extraHeaders) {
      for (Object o : extraHeaders) {
        if (o instanceof Integer) {
          bb.putInt((Integer) o);
        } else if (o instanceof byte[]) {
          bb.put((byte[]) o);
        } else if (o instanceof Long) {
          bb.putLong((Long) o);
        } else if (o instanceof Short) {
          bb.putShort((Short) o);
        } else {
          assert false : "Unhandled extra header type:  " + o.getClass();
        }
      }
docs: Add the extra headers to the write {@link ByteBuffer}.
  
  @param bb the buffer where to append.
  @param extraHeaders the headers to append.