// Then
        assertNotNull(result);
        assertFalse(result.isEmpty());
        // Check starts with byte at offset 16 (0x10)
        assertTrue(result.startsWith("10111213"));
        assertEquals(64, result.length()); // 32 bytes * 2 chars per byte
    }

    @Test
    @DisplayName("Should handle invalid offset and length parameters")
    void testInvalidParameters() {

    private static Stream<Arguments> valueProvider() {
        return Stream.of(Arguments.of(0, 0L, 0L, 0L, 0L), // all zeros
                Arguments.of(1, 1L, 1L, 1L, 1L), // ones
                Arguments.of(123, 456L, 789L, 101112L, 131415L), // arbitrary positives
                Arguments.of(Integer.MAX_VALUE, Long.MAX_VALUE, Long.MIN_VALUE, 999_999_999_999L, -1L), // extremes
                Arguments.of(-1, -2L, -3L, -4L, -5L) // negative values

    @DisplayName("toByteArray returns mechanismToken reference when present")
    void toByteArrayReturnsToken() throws IOException {
        TestSpnegoToken t = new TestSpnegoToken();
        byte[] raw = new byte[] { 11, 12, 13 };
        t.parse(raw);
        // Current behavior of test impl: returns same reference
        assertSame(raw, t.toByteArray(), "should return the same reference as mechanismToken");
    }

    @Test