WebApplicationInitializer provides a programmatic alternative to the
traditional WEB-INF/web.xml servlet container deployment descriptor
for Servlet API 3.0+ environments.
This is done by building atop the new ServletContainerInitializer
support in Servlet 3.0. See SpringServletContainerInitializer for
complete details. And see WebApplicationInitializer Javadoc for
typical usage examples.
Issue: SPR-7672