* AbstractMapBasedMultimap} calls {@link #createCollection()} to create the collection of values
 * for that key. The subclass should not call {@link #createCollection()} directly, and a new
 * instance should be created every time the method is called.
 *
 * <p>For example, the subclass could pass a {@link java.util.TreeMap} during construction, and
 * {@link #createCollection()} could return a {@link java.util.TreeSet}, in which case the

 * AbstractMapBasedMultimap} calls {@link #createCollection()} to create the collection of values
 * for that key. The subclass should not call {@link #createCollection()} directly, and a new
 * instance should be created every time the method is called.
 *
 * <p>For example, the subclass could pass a {@link java.util.TreeMap} during construction, and
 * {@link #createCollection()} could return a {@link java.util.TreeSet}, in which case the