title: When use AbstractAnnotationConfigDispatcherServletInitializer and WebApplicationInitializer?
body: <p>I am working with Spring 4.0.7</p>
  <p>I did a research about configure Spring MVC through JavaConfig.</p>
  <p>Practically until yesterday I have seen two configurations using these two options</p>
  <ol>
  <li><em>extends</em> <code>AbstractAnnotationConfigDispatcherServletInitializer</code></li>
  <li><em>extends</em> <code>WebMvcConfigurerAdapter</code> <strong>and</strong> <em>implements</em> <code>WebApplicationInitializer</code></li>
  </ol>
  <p><strong>Note</strong>: (2) are two classes, one for extension and the other for implementation</p>
  <p>I am using (2) because I have found many examples where I am able to configure converters, formatters, resources handlers etc…</p>
  <p>But in the latest days I have tried to help a question on StackOverflow and I did realize (1) exists.. I did some overview on Google about (1) and exists some examples working with (1)</p>
  <p>My question is how the title of this post describe.</p>
  <p>Thank You</p>