* See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.collect.Lists.newArrayListWithExpectedSize;
import static com.google.common.collect.Lists.transform;
import static java.lang.Math.min;
import static java.util.concurrent.Executors.newFixedThreadPool;

import com.google.common.base.Function;

   * Sets.cartesianProduct with those, then transforms the result to unwrap the Optionals.
   */
  private Iterable<List<Object>> buildCartesianProduct(Set<?>... sets) {
    List<Set<Optional<?>>> optionalSets = Lists.newArrayListWithExpectedSize(sets.length);
    for (Set<?> set : sets) {
      Set<Optional<?>> optionalSet =
          Sets.newLinkedHashSet(Iterables.transform(set, NULLABLE_TO_OPTIONAL));
      optionalSets.add(optionalSet);
    }