docs: public static HttpContextActivationFilter getContextActivationFilter(BeanManagerImpl manager, ServletContext context) {
          HttpContextActivationFilter filter = manager.getServices().get(HttpContextActivationFilter.class);
          final String pattern = context.getInitParameter(InitParameters.CONTEXT_MAPPING);
          if (filter == AcceptingHttpContextActivationFilter.INSTANCE) {
              // SPI has precedence. If a filter was not set through SPI let's see if a mapping is set in web.xml
              if (pattern != null) {
                  return new RegexHttpContextActivationFilter(pattern);
              }
          } else if (pattern != null) {
              ServletLogger.LOG.webXmlMappingPatternIgnored(pattern);
          }
          return filter;
      }