JSTL - using variables in an xpath?

Question

Here is what I would like to do:

Answer 1

Found the answer:

Using JSTL Data as XPath Variables

Scoped variables can be used in XPath expressions ($implicitObject:variableName) similar to how they are used in EL (${implicitObject.variableName}). If the implicit object is omitted, scopes will be searched in standard order. Note that the “.” and “[]” notations cannot be used for accessing bean properties.

from the JSTL Quick Reference Sheet (pdf)

So my code becomes: