* ImmutableSet#builder}.
     */
    public Builder() {
      super(DEFAULT_INITIAL_CAPACITY);
    }

    Builder(int capacity) {
      super(capacity);
      this.hashTable = new @Nullable Object[chooseTableSize(capacity)];
    }

    /**
     * Adds {@code element} to the {@code ImmutableSet}. If the {@code ImmutableSet} already

     */
    @CheckForNull private SetBuilderImpl<E> impl;
    boolean forceCopy;

    public Builder() {
      this(0);
    }

    Builder(int capacity) {
      if (capacity > 0) {
        impl = new RegularSetBuilderImpl<>(capacity);
      } else {
        impl = EmptySetBuilderImpl.instance();
      }
    }

    Builder(@SuppressWarnings("unused") boolean subclass) {