public int positionBitsToShift()
    {
        return positionBitsToShift;
    }
@Test
    void shouldOverridePositionBitsToShift()
    {
        final int positionBitsToShift = -6;
        final int newPositionBitsToShift = 20;
        final Header header = new Header(42, positionBitsToShift);
        assertEquals(positionBitsToShift, header.positionBitsToShift());

        header.positionBitsToShift(newPositionBitsToShift);
        assertEquals(newPositionBitsToShift, header.positionBitsToShift());
    }