#vulnerable code 
                                private boolean testCustomWorkflow(int port) {
        ClientCommandConfig clientCommandConfig = new ClientCommandConfig(new GeneralDelegate());
        TlsConfig config = clientCommandConfig.createConfig();
        config.setHost("localhost:" + port);
        config.setTlsTimeout(TIMEOUT);
        config.setWorkflowTraceType(WorkflowTraceType.CLIENT_HELLO);

        TlsContext tlsContext = new TlsContext(config);
        config.setWorkflowTrace(new WorkflowTrace());

        WorkflowTrace trace = tlsContext.getWorkflowTrace();
        trace.add(MessageActionFactory.createAction(ConnectionEnd.CLIENT, ConnectionEnd.CLIENT, new ClientHelloMessage(
                config)));
        trace.add(MessageActionFactory.createAction(ConnectionEnd.CLIENT, ConnectionEnd.SERVER, new ServerHelloMessage(
                config), new CertificateMessage(config), new ServerHelloDoneMessage(config)));

        trace.add(MessageActionFactory.createAction(ConnectionEnd.CLIENT, ConnectionEnd.CLIENT,
                new RSAClientKeyExchangeMessage(config), new ChangeCipherSpecMessage(config), new FinishedMessage(
                        config)));
        trace.add(MessageActionFactory.createAction(ConnectionEnd.CLIENT, ConnectionEnd.SERVER,
                new ChangeCipherSpecMessage(config), new FinishedMessage(config)));
        WorkflowExecutor workflowExecutor = WorkflowExecutorFactory.createWorkflowExecutor(config.getExecutorType(),
                tlsContext);
        try {
            workflowExecutor.executeWorkflow();
        } catch (WorkflowExecutionException E) {
            return false;
        }

        return !(tlsContext.getWorkflowTrace()
                .getActuallyRecievedHandshakeMessagesOfType(HandshakeMessageType.FINISHED).isEmpty());
    } 
                            #location 12 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                private boolean testCustomWorkflow(int port) {
        ClientCommandConfig clientCommandConfig = new ClientCommandConfig(new GeneralDelegate());
        TlsConfig config = clientCommandConfig.createConfig();
        config.setHost("localhost:" + port);
        config.setTlsTimeout(TIMEOUT);
        config.setWorkflowTraceType(WorkflowTraceType.CLIENT_HELLO);

        TlsContext tlsContext = new TlsContext(config);
        config.setWorkflowTrace(new WorkflowTrace());

        WorkflowTrace trace = config.getWorkflowTrace();
        trace.add(MessageActionFactory.createAction(ConnectionEnd.CLIENT, ConnectionEnd.CLIENT, new ClientHelloMessage(
                config)));
        trace.add(MessageActionFactory.createAction(ConnectionEnd.CLIENT, ConnectionEnd.SERVER, new ServerHelloMessage(
                config), new CertificateMessage(config), new ServerHelloDoneMessage(config)));

        trace.add(MessageActionFactory.createAction(ConnectionEnd.CLIENT, ConnectionEnd.CLIENT,
                new RSAClientKeyExchangeMessage(config), new ChangeCipherSpecMessage(config), new FinishedMessage(
                        config)));
        trace.add(MessageActionFactory.createAction(ConnectionEnd.CLIENT, ConnectionEnd.SERVER,
                new ChangeCipherSpecMessage(config), new FinishedMessage(config)));
        WorkflowExecutor workflowExecutor = WorkflowExecutorFactory.createWorkflowExecutor(config.getExecutorType(),
                tlsContext);
        try {
            workflowExecutor.executeWorkflow();
        } catch (WorkflowExecutionException E) {
            return false;
        }

        return !(tlsContext.getWorkflowTrace()
                .getActuallyRecievedHandshakeMessagesOfType(HandshakeMessageType.FINISHED).isEmpty());
    }