docs: public int getMnemonic() {
          int mnemonic = KeyEvent.VK_UNDEFINED;
          if (!MAC_OS_X) {
              int index = getMnemonicIndex();
              if ((index >= 0) && ((index + 1) < myAnnotatedString.length())) {
                  mnemonic = Character.toUpperCase(myAnnotatedString.charAt(index + 1));
              }
          }
          return mnemonic;
      }