Cannot configure an H2 XA datasource due to missing service

Configuring an XA H2 datasource in standalone.xml (7.1.0.Alpha2-SNAPSHOT) fails with an unsatisfied service dependency:

14:13:15,611 INFO [org.jboss.as.controller] (Controller Boot Thread) JBAS014774: Service status report
JBAS014775: New missing/unsatisfied dependencies:
service jboss.data-source.java:jboss/datasources/ExampleDS (missing) dependents: [service jboss.jaxr.as.bootstrap]

14:13:15,618 ERROR [org.jboss.as] (Controller Boot Thread) JBoss AS 7.1.0.Alpha2-SNAPSHOT "Ahoy!" started (with errors) in 4061ms - Started 154 of 217 services (1 services failed or missing dependencies, 60 services are passive or on-demand)

My XA datasorce is configured as follows:

<xa-datasource jndi-name="java:jboss/datasources/H2XADS" enabled="true"
use-java-context="true" pool-name="H2XADS">
<xa-datasource-property name="URL">jdbc:h2:mem:test</xa-datasource-property>
<driver>h2</driver>
<xa-pool></xa-pool>
<security>
<user-name>sa</user-name>
<password>sa</password>
</security>
</xa-datasource>