java - web.xml can't find dispatcherServlet's servletMapping -

building spring web maven project in sts; can't seem web.xml editor find servletmapping dispatcherservlet, despite being right there. keeps telling me servlet name - "the value not among possible selections." dropdown list flutters it's looking, there no options. web.xml:

<context-param>     <param-name>contextconfiglocation</param-name>     <param-value>classpath:spring/application-config.xml</param-value> </context-param>  <listener>     <listener-class>org.springframework.web.context.contextloaderlistener</listener-class> </listener>   <!--     - servlet dispatches request registered handlers (controller implementations). --> <servlet>     <servlet-name>dispatcherservlet</servlet-name>     <servlet-class>org.springframework.web.servlet.dispatcherservlet</servlet-class>     <init-param>         <param-name>contextconfiglocation</param-name>         <param-value>/web-inf/mvc-config.xml</param-value>     </init-param>     <load-on-startup>1</load-on-startup> </servlet>   <servlet-mapping>     <servlet-name>dispatcherservlet</servlet-name>     <url-pattern>/</url-pattern> </servlet-mapping> 

and here's error i'm getting: