checkEntryNotNull(key, value);
      keys[size] = key;
      values[size] = value;
      size++;
      return this;
    }

    /**
     * Adds the given {@code entry} to the map, making it immutable if necessary. Duplicate keys,
     * according to the comparator (which might be the keys' natural order), are not allowed, and
     * will cause {@link #build} to fail.
     *
     * @since 11.0
     */