<a th:href="@{${flowExecutionUrl}(_eventId=selectPaymentMethod,type=*{paymentMethod.name})}">
  <img th:src="@{|*{paymentMethod.logo}|}" class="img-thumbnail" src="../resources/images/paypal-logo.png" alt="" />
</a>

http://localhost:8080/payments/checkout-widget/session/1/checkout?_eventId=selectPaymentMethod&type=Google+Checkout

@Configuration
@AutoConfigureAfter(MvcConfig.class)
public class WebflowConfig extends AbstractFlowConfiguration {

    @Autowired
    private SpringTemplateEngine templateEngine;

    @Bean
    public FlowExecutor flowExecutor() {
        return getFlowExecutorBuilder(flowRegistry())
                .addFlowExecutionListener(new SecurityFlowExecutionListener())
                .build();
    }

    @Bean
    public FlowDefinitionRegistry flowRegistry() {
        return getFlowDefinitionRegistryBuilder(flowBuilderServices())
                .addFlowLocation("classpath:/templates/checkout.xml", "checkout")
                .build();
    }

    @Bean
    public FlowBuilderServices flowBuilderServices() {
        return getFlowBuilderServicesBuilder()
                .setViewFactoryCreator(mvcViewFactoryCreator())
                .setDevelopmentMode(true)
                .build();
    }

    @Bean
    public FlowController flowController() {
        FlowController flowController = new FlowController();
        flowController.setFlowExecutor(flowExecutor());
        return flowController;
    }

    @Bean
    public FlowHandlerMapping flowHandlerMapping() {
        FlowHandlerMapping flowHandlerMapping = new FlowHandlerMapping();
        flowHandlerMapping.setFlowRegistry(flowRegistry());
        flowHandlerMapping.setOrder(-1);
        return flowHandlerMapping;
    }

    @Bean
    public FlowHandlerAdapter flowHandlerAdapter() {
        FlowHandlerAdapter flowHandlerAdapter = new FlowHandlerAdapter();
        flowHandlerAdapter.setFlowExecutor(flowExecutor());
        flowHandlerAdapter.setSaveOutputToFlashScopeOnRedirect(true);
        return flowHandlerAdapter;
    }

    @Bean
    public AjaxThymeleafViewResolver thymeleafViewResolver() {
        AjaxThymeleafViewResolver viewResolver = new AjaxThymeleafViewResolver();
        viewResolver.setViewClass(FlowAjaxThymeleafView.class);
        viewResolver.setTemplateEngine(templateEngine);
        return viewResolver;
    }

    @Bean
    public MvcViewFactoryCreator mvcViewFactoryCreator() {
        List<ViewResolver> viewResolvers = new ArrayList<>();
        viewResolvers.add(thymeleafViewResolver());

        MvcViewFactoryCreator mvcViewFactoryCreator = new MvcViewFactoryCreator();
        mvcViewFactoryCreator.setViewResolvers(viewResolvers);
        mvcViewFactoryCreator.setUseSpringBeanBinding(true);
        return mvcViewFactoryCreator;
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/webflow
            http://www.springframework.org/schema/webflow/spring-webflow-2.0.xsd">

    <on-start>
        <set name="flowScope.paymentMethods" value="checkoutService.paymentMethods"/>
    </on-start>

    <view-state id="payment-methods" view="payment-methods">
        <transition on="selectPaymentMethod" to="new-details"/>
    </view-state>

    <view-state id="new-details" view="new-details">
        <transition on="submitDetails"/>
    </view-state>

    <view-state id="summary" view="summary">
        <transition on="completeDetails" to="completed"/>
    </view-state>

    <end-state id="cancelled" view="externalRedirect:contextRelative:/home.do"/>
    <end-state id="completed" view="externalRedirect:contextRelative:/home.do"/>

    <global-transitions>
        <transition on="cancelCheckout" to="cancelled"/>
    </global-transitions>
</flow>

@Controller
@RequestMapping(value = "/payments/checkout-widget/session/{sessionId}")
@SessionAttributes({"paymentMethods", "redirectUrls", "cardDetails"})
public class WelcomeController {

    @Inject
    private CheckoutWidgetSessionService checkoutWidgetSessionService;

    @Inject
    private CheckoutService checkoutService;

    @RequestMapping(value = "/checkout", method = RequestMethod.GET)
    public String intro(
            @NotNull @PathVariable("sessionId") String sessionId,
            Model model) {
        System.out.println("Session ID:" + sessionId);

        model.addAttribute("paymentMethods", checkoutService.getPaymentMethods());
        model.addAttribute("deliveryAddress", checkoutService.getDeliveryAddress());
        model.addAttribute("date",new Date().toString());

        return "payment-methods";
    }
}

<html>
    <head>
        <meta charset="utf-8"/>
        <meta http-equiv="X-UA-Compatible" content="IE=edge"/>
        <meta name="viewport" content="width=device-width, initial-scale=1"/>

        <link rel="stylesheet"
              th:href="@{/css/bootstrap.min.css}"
              href="../resources/css/bootstrap.min.css"/>
    </head>
    <body>
        <div class="container">
            <h1 th:text="#{payment.methods.title}">Payment Methods</h1>
            <br/>

            <p th:text="#{payment.methods.label}">Please select a payment method:</p>

            <div class="row">
                <div class="col-sm-2 col-xs-4 col-md-1 col-lg-1" th:each="paymentMethod : ${paymentMethods}">
                    <a th:href="@{${flowExecutionUrl}(_eventId=selectPaymentMethod,type=*{paymentMethod.name})}">
                        <img th:src="@{|*{paymentMethod.logo}|}" class="img-thumbnail" src="../resources/images/paypal-logo.png" alt="" />
                    </a>
                </div>

            </div>

        </div>
        <!-- jQuery (necessary for Bootstrap's JavaScript plugins) -->
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
        <!-- Include all compiled plugins (below), or include individual files as needed -->
        <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.1/js/bootstrap.min.js"></script>

    </body>
</html>