public static String decodeBody(byte[] body, byte dataCoding, String defaultEncoding)
            throws UnsupportedEncodingException {
        Alphabet alphabet = Alphabet.parseDataCoding(dataCoding);
        if (body == null || SmppUtils.is8Bit(alphabet)) {
            return null;
        }
        switch (alphabet) {
            case ALPHA_IA5:
                return new String(body, StandardCharsets.US_ASCII);
            case ALPHA_LATIN1:
                return new String(body, StandardCharsets.ISO_8859_1);
            case ALPHA_UCS2:
                return new String(body, StandardCharsets.UTF_16BE);
            default:
                return new String(body, defaultEncoding);
        }
    }
@Test
    void testDecodeBodyWhenBodyIs8bitShouldReturnNull() throws UnsupportedEncodingException {
        byte[] body = new byte[] { 0, 1, 2, 3, 4 };
        Assertions.assertNull(SmppUtils.decodeBody(body, Alphabet.ALPHA_8_BIT.value(), "X-Gsm7Bit"));
    }