docs: public void compact() {
      if (keys.length > size) {
        Class<?>[] newKeys = new Class<?>[size];
        Object[] newVals = new Object[size];
        System.arraycopy(keys, 0, newKeys, 0, size);
        System.arraycopy(values, 0, newVals, 0, size);
        keys = newKeys;
        values = newVals;
      }
    }