builder.put(key, set);
        size += set.size();
      }
    }

    return new ImmutableSetMultimap<>(builder.buildOrThrow(), size, valueComparator);
  }

  /**
   * Returned by get() when a missing key is provided. Also holds the comparator, if any, used for
   * values.
   */
  private final transient ImmutableSet<V> emptySet;

  ImmutableSetMultimap(
      ImmutableMap<K, ImmutableSet<V>> map,

   * for (E e : occurrencesToRemove) {
   *   multisetToModify.remove(e);
   * }
   * }</pre>
   *
   * @return {@code true} if {@code multisetToModify} was changed as a result of this operation
   * @since 10.0 (missing in 18.0 when only the overload taking an {@code Iterable} was present)
   */
  @CanIgnoreReturnValue
  public static boolean removeOccurrences(
      Multiset<?> multisetToModify, Multiset<?> occurrencesToRemove) {