@Test
    public void testValidSaslPlainOverSsl() throws Exception {
        String node = "0";
        SecurityProtocol securityProtocol = SecurityProtocol.SASL_SSL;
        configureMechanisms("PLAIN", Collections.singletonList("PLAIN"));

        server = createEchoServer(securityProtocol);
        checkAuthenticationAndReauthentication(securityProtocol, node);
    }
Tests good path SASL/PLAIN client and server channels using SSL transport layer.
Also tests successful re-authentication.
clients/src/test/java/org/apache/kafka/common/security/authenticator/SaslAuthenticatorTest.java