public static String toHexStringPadded(byte[] src) {
        return toHexStringPadded(src, 0, src.length);
    }
@Test
    public void testToHexStringPadded() {
        assertThat(toHexStringPadded(new byte[]{0}), is("00"));
        assertThat(toHexStringPadded(new byte[]{1}), is("01"));
        assertThat(toHexStringPadded(new byte[]{0, 0}), is("0000"));
        assertThat(toHexStringPadded(new byte[]{1, 0}), is("0100"));
        assertThat(toHexStringPadded(EmptyArrays.EMPTY_BYTES), is(""));
    }