AbstractAnnotationConfigDispatcherServletInitializer conflict with web.xml for Spring Security

When we use Spring Security in our application, we  extend 
AbstractAnnotationConfigDispatcherServletInitializer 
to include our WebSecurityConfigurerAdapter implementation into the root context.

However this can throw the following error during application startup

"Cannot initialize context because there is already a root application context present - check whether you have multiple ContextLoader* definitions in your webxml!"

One reason the above may happen is because we could be having the following snippet in our web.xml

<listener>

<listener-class> org.springframework.web.context.ContextLoaderListener
</listener-class>

</listener>

<context-param>

<param-name>contextConfigLocation</param-name>

<param-value>/WEB-INF/applicationContext.xml</param-value>

</context-param> 

which already creates the root context for the Application from
/WEB-INF/applicationContext.xml.

Servlet 3.X specification allows us to do away with XML and create Java-based configuration. So we can comment the above snippet in web.xml and add the following method in our AbstractAnnotationConfigDispatcherServletInitializer subclass to remove the above error.

@Override

protected WebApplicationContext createRootApplicationContext() {

// TODO Auto-generated method stub

return new XmlWebApplicationContext();

}

The no-arg XmlWebApplicationContext instance uses

"/WEB-INF/applicationContext.xml" by default.