Context and parent have been set. It also assumes that any
 properties exposed as attributes have been set too. When this method is invoked, the body has not yet been
 evaluated.

 <p>
 This method returns Tag.EVAL_BODY_INCLUDE or BodyTag.EVAL_BODY_BUFFERED to indicate that the body of the action
 should be evaluated or SKIP_BODY to indicate otherwise.

 <p>
 When a Tag returns EVAL_BODY_INCLUDE the result of evaluating the body (if any) is included into the current
 "out" JspWriter as it happens and then d