code: public static String getContextRootNotFoundMessage() {
          // this does not return a default string, since the caller may (and does in our case) choose to build a runtime
          // dependent string.
  
          HttpDispatcher f = instance.get().get();
          if (f != null)
              return f.appOrContextRootNotFound;
  
          return null;
      }
docs: Get the value for the appOrContextRootMissingMessage custom property. return null if it was not set.
  
  @return String the value for the appOrContextRootMissingMessage custom property, null if it was not set.