public static byte[] readFixedLengthBytes(byte[] data, int index, int length) {
        byte[] bytes = new byte[length];
        System.arraycopy(data, index, bytes, 0, length);
        return bytes;
    }
@Test
	public void testReadFixedLengthBytes() {
		Assert.assertArrayEquals(new byte[] {}, ByteHelper.readFixedLengthBytes(new byte[0], 0, 0));
	}