public byte[] requestPrincipal() {
        return data.requestPrincipal();
    }
@Test
    public void testGetPrincipal() {
        KafkaPrincipal kafkaPrincipal = new KafkaPrincipal(KafkaPrincipal.USER_TYPE, "principal", true);
        DefaultKafkaPrincipalBuilder kafkaPrincipalBuilder = new DefaultKafkaPrincipalBuilder(null, null);

        EnvelopeRequest.Builder requestBuilder = new EnvelopeRequest.Builder(ByteBuffer.allocate(0),
            kafkaPrincipalBuilder.serialize(kafkaPrincipal), "client-address".getBytes());
        EnvelopeRequest request = requestBuilder.build(EnvelopeRequestData.HIGHEST_SUPPORTED_VERSION);
        assertEquals(kafkaPrincipal, kafkaPrincipalBuilder.deserialize(request.requestPrincipal()));
    }