public static String generateToken(final String userName, final String key, final String clientId) {
        return generateToken(userName, key, clientId, null);
    }
@Test
    public void testGenerateToken() {
        String token = JwtUtils.generateToken("userName", KEY, "clientId");
        assertThat(token, notNullValue());
        assertThat(JwtUtils.getIssuer(token), is("userName"));
        assertThat(JwtUtils.getClientId(token), is("clientId"));
    }