I have a web application using Spring 2.5.6 and Spring Security 2.0.4. I have implemented a working login page, which authenticates the user against a web service. The authentication is done by defining a custom authentincation manager, like this:

<beans:bean id="customizedFormLoginFilter"
    class="org.springframework.security.ui.webapp.AuthenticationProcessingFilter">
    <custom-filter position="AUTHENTICATION_PROCESSING_FILTER" />
    <beans:property name="defaultTargetUrl" value="/index.do" />
    <beans:property name="authenticationFailureUrl" value="/login.do?error=true" />
    <beans:property name="authenticationManager" ref="customAuthenticationManager" />
    <beans:property name="allowSessionCreation" value="true" />
</beans:bean>

<beans:bean id="customAuthenticationManager"
    class="com.sevenp.mobile.samplemgmt.web.security.CustomAuthenticationManager">
    <beans:property name="authenticateUrlWs" value="${WS_ENDPOINT_ADDRESS}" />
</beans:bean>

The authentication manager class:

public class CustomAuthenticationManager implements AuthenticationManager, ApplicationContextAware {

    @Transactional
    @Override
    public Authentication authenticate(Authentication authentication) throws AuthenticationException {

                //authentication logic

        return new UsernamePasswordAuthenticationToken(principal, authentication.getCredentials(),
                grantedAuthorityArray);
    }

The essential part of the login jsp looks like this:

<c:url value="/j_spring_security_check" var="formUrlSecurityCheck"/>
<form method="post" action="${formUrlSecurityCheck}">
    <div id="errorArea" class="errorBox"> 
       <c:if test="${not empty param.error}">
          ${sessionScope["SPRING_SECURITY_LAST_EXCEPTION"].message}
      </c:if>
  </div>
    <label for="loginName">
        Username:           
        <input style="width:125px;" tabindex="1" id="login" name="j_username" />
    </label>

    <label for="password">
        Password:           
        <input style="width:125px;" tabindex="2" id="password" name="j_password" type="password" />
    </label>
    <input type="submit" tabindex="3" name="login" class="formButton" value="Login" />
</form>

Now the problem is that the application should use Spring Web Flow. After the application was configured to use Spring Web Flow, the login does not work anymore - the form action to "/j_spring_security_check" results in a blank page without error message. What is the best way to adapt the existing login process so that it works with Spring Web Flow?