* read operations will work correctly. To allow concurrent update operations, wrap your multimap
 * with a call to {@link Multimaps#synchronizedListMultimap}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
 *
 * @author Jared Levy
 * @since 2.0
 */

import static com.google.common.collect.Multimaps.filterKeys;
import static com.google.common.collect.Multimaps.filterValues;
import static com.google.common.collect.Multimaps.synchronizedListMultimap;
import static com.google.common.collect.testing.Helpers.mapEntry;
import static com.google.common.collect.testing.features.CollectionFeature.ALLOWS_NULL_VALUES;

 * read operations will work correctly. To allow concurrent update operations, wrap your multimap
 * with a call to {@link Multimaps#synchronizedListMultimap}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
 *
 * @author Mike Bostock
 * @since 2.0
 */

   * {@code map} and the instances generated by {@code factory} are. Concurrent read operations will
   * work correctly. To allow concurrent update operations, wrap the multimap with a call to {@link
   * #synchronizedListMultimap}.
   *
   * <p>Call this method only when the simpler methods {@link ArrayListMultimap#create()} and {@link
   * LinkedListMultimap#create()} won't suffice.
   *

   * {@code map} and the instances generated by {@code factory} are. Concurrent read operations will
   * work correctly. To allow concurrent update operations, wrap the multimap with a call to {@link
   * #synchronizedListMultimap}.
   *
   * <p>Call this method only when the simpler methods {@link ArrayListMultimap#create()} and {@link
   * LinkedListMultimap#create()} won't suffice.
   *