"Webapp must not override any class in teh java.* or javax.* namespaces"

[Himai Minh]

On p.647 of Head First book,

Option C and D are incorrect because webapp must not override any class in the java.* or javax.* namespace
Option A is correct.

Which statement concerning the container class loader are true?
Option A. web application should not attempt to override container implementation classes.
....
Option C. A web application may override any J2ED classes in javax.* namespace
Option D. A web developer may override J2EE platform classes provided they are not contained in a library JAR within a WAR.

But as I learn, the web application can override :
1. doStartTag() method of javax.servlet.jsp.TagSupport,
2. contextInitialized () method of javax.servlet.ServletContextListener, or
3. doPost method in javax.servlet.HttpServlet...

[Frits Walraven]

Overriding classes in this part of the specs means that you are not allowed to create your own implementation of the classes: you should use the ones that come with the EE-container.

For instance: you are allowed to extend the TagSupport class but you are not allowed to replace the TagSupport class with your own implementation.