问如何获取mule流中的安全上下文或安全主引用

EN

import org.mule.api.MuleEventContext;
import org.mule.api.lifecycle.Callable;
import org.mule.api.security.Authentication;
import org.springframework.security.core.userdetails.UserDetails;

public class GetSecurityPrincipalCallable implements Callable {

@Override
public Object onCall(MuleEventContext eventContext) throws Exception {
    Authentication auth = eventContext.getSession().getSecurityContext()
            .getAuthentication();
    UserDetails principal = (UserDetails) auth.getPrincipal();
    System.out.println("username is : " + principal.getUsername());
    eventContext.getMessage().setInvocationProperty("user", principal);
    return null;
  }

}