final Iterator<? extends Entry<? extends E>> iterator1 = multiset1.entrySet().iterator();
        final Iterator<? extends Entry<? extends E>> iterator2 = multiset2.entrySet().iterator();
        // TODO(lowasser): consider making the entries live views
        return new AbstractIterator<Entry<E>>() {
          @Override
          @CheckForNull
          protected Entry<E> computeNext() {
            if (iterator1.hasNext()) {

      alternatingKeysAndValues[2 * size] = key;
      alternatingKeysAndValues[2 * size + 1] = value;
      size++;
      return this;
    }

    /**
     * Adds the given {@code entry} to the map, making it immutable if necessary. If the same key is
     * put more than once, {@link #buildOrThrow} will fail, while {@link #buildKeepingLast} will
     * keep the last value put for that key.
     *
     * @since 11.0

    public Builder<R, C, V> put(R rowKey, C columnKey, V value) {
      cells.add(cellOf(rowKey, columnKey, value));
      return this;
    }

    /**
     * Adds the given {@code cell} to the table, making it immutable if necessary. Duplicate key
     * pairs are not allowed and will cause {@link #build} to fail.
     */
    @CanIgnoreReturnValue

   * is unnecessary; for example, {@code copyOf(copyOf(anArrayList))} will copy the data only once.
   * This reduces the expense of habitually making defensive copies at API boundaries. However, the
   * precise conditions for skipping the copy operation are undefined.
   *
   * @throws NullPointerException if any of {@code elements} is null