Compartilhando objeto entre telas, usando o Spring Webflow

Estou tentando criar algo que se pareça com um processo de várias telas para configurar uma reserva, por exemplo.

Tela 1 Adicione informações pessoaisTela 2 Informações de contatoTela 3 Resumo e confirme

Eu configurei meu webflow .jsp e xml e todas as classes, mas estou tendo problemas para vinculá-las. Eu quero criar uma classe de conta no início do fluxo. Quando a primeira tela é preenchida, as informações são armazenadas nessa classe. Quando na tela final, o usuário pode visualizar o resumo com base nas informações que ele forneceu e revisar, se necessário, quando ele voltar para a primeira tela, as informações serão preenchidas para ele, para que ele não tenha que entrar novamente.

Sinto muito pela parede do código. Tentei minimizá-lo para os possíveis lugares para um erro que eu poderia pensar.

Meu flow-config.xml

<?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>
        <evaluate expression="BookingManagementService.createBooking()" result="flowScope.booking" />
    </on-start>

    <view-state id="flow-config"  view="booking/BookingIdentificationScreen" model="booking">
    <binder>
        <binding property="username" />
    </binder>
    <transition on="next" to="enterContactDetails"/>
    <transition on="cancel" to="cancel"/>
</view-state>
    ... 
</flow>

Meu servlet-context.xml geral

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

    <annotation-driven />

    <resources mapping="/resources/**" location="/resources/" />

    <beans:bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <beans:property name="prefix" value="/WEB-INF/views/" />
        <beans:property name="suffix" value=".jsp" />
    </beans:bean>

    <context:component-scan base-package="com.mycompany.myapp" />

    <beans:bean id="handlerMapping" class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping" />
    <beans:bean name="/index.do" class="com.mycompany.myapp.IndexController" />
    <beans:bean name="/home.do" class="com.mycompany.myapp.HomeController" />

    <beans:bean class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
        <beans:property name="mappings" value="/account/flow-config.do=flowController" />
        <beans:property name="alwaysUseFullPath" value="true"/>
    </beans:bean>

    <!-- SPRING WEB FLOW STUFF -->
    <beans:bean id="flowController" class="org.springframework.webflow.mvc.servlet.FlowController">
        <beans:property name="flowExecutor" ref="flowExecutor"/>
    </beans:bean>

    <webflow:flow-executor id="flowExecutor" flow-registry="flowRegistry"/>

    <webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices">
        <webflow:flow-location path="/WEB-INF/config/flow-config.xml"/>
    </webflow:flow-registry>

    <webflow:flow-builder-services id="flowBuilderServices" view-factory-creator="viewFactoryCreator"/>

    <beans:bean id="viewFactoryCreator" class="org.springframework.webflow.mvc.builder.MvcViewFactoryCreator">
        <beans:property name="viewResolvers">
            <beans:list>
                <beans:ref bean="viewResolver"/>
            </beans:list>
        </beans:property>
    </beans:bean>

</beans:beans>

BookingManagementService.java

@Service("bookingService")
public class BookingManagementService{
    @Transactional(readOnly = true)
    public BookingIpl createBooking(Long hotelId, String username) {
        BookingIpl booking= new BookingIpl();
        return booking;
    }
}

BookingIpl.java

@Entity
public class BookingIpl implements Serializable {
    public String username;
    ...
}

IndexController

   @Controller
   public class IndexController extends AbstractController {
    private BookingManagementService bookingService;

    @Autowired
    public IndexController(BookingManagementService bookingService) {
        this.bookingService = bookingService;
    }
    @Override
    protected ModelAndView handleRequestInternal(HttpServletRequest arg0,
            HttpServletResponse arg1) throws Exception {
        return new ModelAndView("index");
    }
}

então nos meus scripts java para a primeira tela eu teria algo como:

<form:form modelAttribute="booking" action="${flowExecutionUrl}" method="post">
     <form:input type="text" path="username"/>
</form:form>

e após o prompt para a próxima tela eu quero retornar o valor em um resumo por exemplo

 <form:form modelAttribute="booking" action="${flowExecutionUrl}" method="post">
         <spring:bind path="username">${status.value}</spring:bind>
    </form:form>

O erro que estou recebendo é ao longo da linha de:

SEVERE: Servlet.service() for servlet [appServlet] in context with path [/myapp] threw exception [Request processing failed; nested exception is org.springframework.webflow.execution.ActionExecutionException: Exception thrown executing [AnnotatedAction@778e65f2 targetAction = [EvaluateAction@25c73030 expression = bookingService.createBooking(), resultExpression = flowScope.booking], attributes = map[[empty]]] in state 'null' of flow 'flow-config' -- action execution attributes were 'map[[empty]]'] with root cause
org.springframework.expression.spel.SpelEvaluationException: EL1008E:(pos 0): Field or property 'bookingService' cannot be found on object of type 'org.springframework.webflow.engine.impl.RequestControlContextImpl'

Eu tentei outro método para fazer tudo isso que está definindo um bean no meu servlet da seguinte forma:

<beans:bean id="bookingBean" class="com.mycompany.myapp.BookingIpl" scope="prototype" />

mas isso não ajudou, deu o mesmo erro.

Eu sou muito novo no fluxo da web e na primavera, então, por favor, me perdoe se o erro que cometi foi algo óbvio.

Obrigado

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