用于按条件设置经纪经纪人中继和简单经纪人的XML配置

Question

我配置了春季网络套接字消息代理：

<websocket:message-broker application-destination-prefix="/portal">
     <websocket:stomp-endpoint path="/notification" allowed-origins="*">
          <websocket:sockjs/>
     </websocket:stomp-endpoint>
     <websocket:stomp-broker-relay prefix="/topic/,/queue/" />
</websocket:message-broker>

我想配置另一个网络套接字消息代理：

<websocket:message-broker application-destination-prefix="/portal">
     <websocket:stomp-endpoint path="/notification" allowed-origins="*">
          <websocket:sockjs/>
     </websocket:stomp-endpoint>
     <websocket:simple-broker/>
</websocket:message-broker>

如何通过$ {simpleBorkerEnabled}之类的条件启用或禁用它？