The persistent attribute of the <gfe:replicated-region> element does not accept a variable

The 'persistent' attribute of the replicated-region definition does not allow a property variable, it only accepts a boolean.

<gemfire:replicated-region id="someRegionBean"
name="someRegion" persistent="${persistence.enabled}" cache-ref="gemfireCache">
...

2011-04-21 14:07:34,091 ERROR [main] - Context initialization failed
org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 40 in XML document from ServletContext resource [/WEB-INF/spring/test-data-context.xml] is invalid; nested exception is org.xml.sax.SAXParseException: cvc-datatype-valid.1.2.1: '${persistence.enabled}' is not a valid value for 'boolean'.

I would like to control the caches persistent state from an external property file.