code: @CanIgnoreReturnValue
    @Override
    public SortedSet<V> removeAll(@NullableDecl Object key) {
      return (SortedSet<V>) super.removeAll(key);
    }
docs: Removes all values associated with a given key. The returned collection is immutable.
  
  <p>Because a {@code SortedSetMultimap} has unique sorted values for a given key, this method
  returns a {@link SortedSet}, instead of the {@link Collection} specified in the {@link
  Multimap} interface.