On p. 528 of Head First book,
The setJspBody() method will be invoked only if the tag is actually called with a body. If the tag is invoked without a body,
either with an empty tag,or with nothing in between tags, the setJspBody() method will not be called.
So, does it mean setJspBody() method is called by the container when the tag is defined as not empty?
Should the developer call setJspBody within doTag() method?