title: about spring social xml configuration
body: <p>i wonder "#{request.userPrincipal.name}" in configuration blow. when I run my spring social project it always has error at "#{request.userPrincipal.name}", if I set a value such as "123" my project runs well. what's wrong and is there any other configuration instead of "#{request.userPrincipal.name}" ?</p>
  
  <pre><code>&lt;bean id="connectionRepository" factory-method="createConnectionRepository" factory-bean="usersConnectionRepository" scope="request"&gt;
      &lt;constructor-arg value="#{request.userPrincipal.name}" /&gt;
      &lt;aop:scoped-proxy proxy-target-class="false" /&gt;
  &lt;/bean&gt;
  </code></pre>