The <es:notNull> tag is used to check if a value is not null. In the case of a String, the <es:notNull> tag is used to check if the String is not null or has a value (more than zero length).
<tagName attribute="value" />
item
Required (Object) - The variable to evaluate.
This example prints a message if an object is not null.
<es:notNull item="<%=value%>"> The value is not null. </es:notNull>