Using an evaluator outside the scope of an entity results in a null context

public class LowerCaseFunctionEvaluator extends Evaluator {
 public String evaluate(String expression, Context context) {
   List l = EvaluatorBag.parseParams(expression, context.getVariableResolver());
   
   if (l.size() != 1) {
     throw new RuntimeException("'toLowerCase' must have only one parameter ");
   }

   return l.get(0).toString().toLowerCase();
 }
}

<dataSource name="..."
            type="..."
            driver="..."
            url="..."
            user="${dataimporter.functions.toLowerCase('THIS_WILL_NOT_WORK')}"
            password="..."/>

<entity name="..."
        dataSource="..."
        query="select * from ${dataimporter.functions.toLowerCase('THIS_WILL_WORK')}"/>