anchor.diff:  
   
   [[howto-add-a-servlet-filter-or-listener]]
  -=== Add a Servlet, Filter, or Listener to an Application
  -There are two ways to add `Servlet`, `Filter`, `ServletContextListener`, and the other
  -listeners supported by the Servlet spec to your application:
  +=== Add a Servlet, Filter, or Listener to a Application
  +In a servlet stack application, i.e. with the `spring-boot-starter-web`, there are two
  +ways to add `Servlet`, `Filter`, `ServletContextListener`, and the other listeners
  +supported by the Servlet API to your application:
   
   * <<howto-add-a-servlet-filter-or-listener-as-spring-bean>>
   * <<howto-add-a-servlet-filter-or-listener-using-scanning>>
  
positive.code: choice: you should select the variant for the chosen Server (Tomcat, Jetty, Reactor Netty,
  Undertow) and the chosen web stack (Servlet or Reactive).
  
  In the following example, we're using Tomcat in a Servlet-based web application:
  
  [source,java,indent=0,subs="verbatim,quotes,attributes"]
  ----
  
negative.code: 
  [[howto-use-another-web-server]]
  === Use Another Web Server
  Many Spring Boot starters include default embedded containers.
  
  * For servlet stack applications, the `spring-boot-starter-web` includes Tomcat by including
  `spring-boot-starter-tomcat`, but you can use `spring-boot-starter-jetty` or
  `spring-boot-starter-undertow` instead.
  * For reactive stack applications, the `spring-boot-starter-webflux` includes  Reactor Netty
  by including `spring-boot-starter-reactor-netty`, but you can use `spring-boot-starter-tomcat`,
  `spring-boot-starter-jetty`, or `spring-boot-starter-undertow` instead.
  
  When switching to a different HTTP server, you need to exclude the default dependencies
  in addition to including the one you need. Spring Boot provides separate starters for
  HTTP servers to help make this process as easy as possible.
  
  The following Maven example shows how to exclude Tomcat and include Jetty for Spring MVC:
  