code: public SnackbarBuilder appendMessage(CharSequence message, @ColorInt int color) {
      initialiseAppendMessages();
      Spannable spannable = new SpannableString(message);
      spannable.setSpan(new ForegroundColorSpan(color), 0, spannable.length(),
          Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
      appendMessages.append(spannable);
      return this;
    }
docs: Add some text to append to the message shown on the Snackbar and a colour to make it.
  
  @param message Text to append to the Snackbar message.
  @param color   Colour to make the appended text.
  @return This instance.