on</code></a> used to calculate the value for the specified attribute or property name, if any. If
 a <a href="../../el/ValueExpression.html" title="class in jakarta.el"><code>ValueExpression</code></a> is set for the <code>channel</code> or <code>scope</code> property, regardless of the
 value, throw an illegal argument exception. If a <a href="../../el/ValueExpression.html" title="class in jakarta.el"><code>ValueExpression</code></a> is set for the <code>user</code> property,
 and the non-null value is no