Jackrabbit - Select node with maximum property value - xpath

Question

Let's say I have several file nodes with a property called foo. In Jackrabbit the xpath query I use to find those nodes by a property value is as follows:
/jcr:root/content/*[jcr:uuid='9b3d22fc-2354-49a6-afd0-9b672ae5a553']//file[foo = 10] order by #score
An oversimplified and raw representation of my repository as XML would look like this:
<content>
<formNode jcrUuid="9b3d22fc-2354-49a6-afd0-9b672ae5a553">
<year>
<month>
<day>
<hour>
<min>
<file foo="4"></file>
<file foo="10"></file>
</min>
</hour>
</day>
<day>
<hour>
<min>
<file foo="10"></file>
</min>
<min>
<file foo="5"></file>
</min>
</hour>
<hour>
<min>
<file foo="6"></file>
</min>
</hour>
</day>
</month>
</year>
</formNode>
</content>
Now. How can I find all the file nodes with the maximum value of foo? Does anyone know how to do this either by using xpath or JCR_SQL2?
I've tried the following queries without success:
Returns all the file nodes under the provided jcr:uuid
/jcr:root/content/*[jcr:uuid='9b3d22fc-2354-49a6-afd0-9b672ae5a553']//file[not(../file/foo > foo)] order by #score
Throws an Exception
jcr:root/content/*[jcr:uuid='9b3d22fc-2354-49a6-afd0-9b672ae5a553']//file[not(//file/foo > foo)] order by #score
Exception:
javax.jcr.query.InvalidQueryException: Unsupported root level query node: org.apache.jackrabbit.spi.commons.query.RelationQueryNode#8fedc
I've also tried the function fn:max. But AFAIK this is a XPATH 2.0 feature, which is not supported by JackRabbit 2.2.13, and I'm forced to use this version of JackRabbit.