* 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.Maps.immutableEntry;
import static com.google.common.collect.Multimaps.filterKeys;
import static com.google.common.collect.Multimaps.synchronizedListMultimap;
import static com.google.common.collect.Multimaps.synchronizedMultimap;
import static com.google.common.collect.Multimaps.synchronizedSetMultimap;