If the value is a negative integer, or the element is not present, the container is free to load the servlet
whenever it chooses. If the value is a positive integer or 0, the container must load and initialize the
servlet as the application is deployed.
Any non-negative value for <load-on-startup> tells the Container to initialize the servlet when the app is deployed (or any time the server restarts).
In FREDERIC ESNAULT notes:
negative or 0 : no preloading; load at first request;
1 or more : servlet loaded at startup.
FE notes is different than the other two versions. Which one is correct?
If 0 means pre-load the servlet, will it take precedence than value 1?