de>FunctionMapper</code> and <code>VariableMapper</code> instances change
 between calling <code>ExpressionFactory.createValueExpression()</code> and any method on
 <code>ValueExpression</code>. Note that within Jakarta Expression Language, the ${} and #{} syntaxes are treated
 identically. This includes the use of VariableMapper and FunctionMapper at expression creation time. Each is invoked
 if not null, independent of whether the #{} or ${} syntax is used for the expression.</dd>
<dd><code>expression</co