According to Servlet 3.0 javadoc ServletContext.getJspConfigDescriptor() must return NULL when there is no jsp configuration: " Returns: the <jsp-config> related configuration that was aggregated from the web.xml and web-fragment.xml descriptor files of the web application represented by this ServletContext, or null if no such configuration exists "
Fixed in trunk and 7.0.x and will be included in 7.0.41 onwards.