*
 * <h2>Collection types</h2>
 *
 * <dl>
 *   <dt>{@link Multimap}
 *   <dd>A new type, which is similar to {@link java.util.Map}, but may contain multiple entries
 *       with the same key. Some behaviors of {@link Multimap} are left unspecified and are provided
 *       only by the subtypes mentioned below.
 *   <dt>{@link ListMultimap}
 *   <dd>An extension of {@link Multimap} which permits duplicate entries, supports random access of