}

    @CanIgnoreReturnValue
    Builder<K, V> combine(Builder<K, V> other) {
      super.combine(other);
      return this;
    }

    @Override
    public ImmutableBiMap<K, V> build() {
      return buildOrThrow();
    }

    @Override
    public ImmutableBiMap<K, V> buildOrThrow() {
      ImmutableMap<K, V> map = super.buildOrThrow();
      if (map.isEmpty()) {
        return of();

     * not allowed, and will cause {@link #build} to fail.
     */
    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> put(K key, V value) {
      super.put(key, value);
      return this;
    }

    /**
     * Adds the given {@code entry} to the bimap. Duplicate keys or values are not allowed, and will
     * cause {@link #build} to fail.
     *
     * @since 19.0
     */

     * not allowed, and will cause {@link #build} to fail.
     */
    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> put(K key, V value) {
      super.put(key, value);
      return this;
    }

    /**
     * Adds the given {@code entry} to the bimap. Duplicate keys or values are not allowed, and will
     * cause {@link #build} to fail.
     *
     * @since 19.0
     */