NullAttributeException is a JspTagException that will be thrown by the JSTL RI handlers when a tag attribute illegally evaluates to 'null'.
Constructs a NullAttributeException with appropriate information.paramtag The name of the tag in which the error occurred.paramatt The attribute value for which the error occurred. super(Resources.getMessage("TAG_NULL_ATTRIBUTE", att, tag));
super(Resources.getMessage("TAG_NULL_ATTRIBUTE", att, tag));