It seems that CLI xa-data-source add command does not allow to specify xa-datasource-properties. As having non empty xa-tadasource-properties map is mandatory, enabling such datasource fails:

[standalone@localhost:9999 xa-datasource-properties] xa-data-source add --name=TestXADS --jndi-name=java:jboss/datasources/TestXADS --driver-name=h2
[standalone@localhost:9999 xa-datasource-properties] xa-data-source enable --name=TestXADS
JBAS014750: Operation handler failed to complete

Server exception:
15:54:56,948 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-7) MSC00001: Failed to start service jboss.data-source.java:jboss/datasources/TestXADS: org.jboss.msc.service.StartException in service jboss.data-source.java:jboss/datasources/TestXADS: JBAS010433: Error during the deployment of TestXADS
at org.jboss.as.connector.subsystems.datasources.AbstractDataSourceService.start(AbstractDataSourceService.java:118)
at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811) [jboss-msc-1.0.2.GA.jar:1.0.2.GA]
at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1746) [jboss-msc-1.0.2.GA.jar:1.0.2.GA]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) [:1.7.0_b147-icedtea]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) [:1.7.0_b147-icedtea]
at java.lang.Thread.run(Thread.java:722) [:1.7.0_b147-icedtea]
Caused by: org.jboss.jca.common.api.validator.ValidateException: IJ010069: Missing required element xa-datasource-property in org.jboss.jca.common.metadata.ds.XADataSourceImpl
at org.jboss.jca.common.metadata.ds.XADataSourceImpl.validate(XADataSourceImpl.java:384)
at org.jboss.jca.common.metadata.ds.XADataSourceImpl.<init>(XADataSourceImpl.java:115)
at org.jboss.as.connector.subsystems.datasources.ModifiableXaDataSource.getUnModifiableInstance(ModifiableXaDataSource.java:372)
at org.jboss.as.connector.subsystems.datasources.XaDataSourceService.getDeployer(XaDataSourceService.java:66)
at org.jboss.as.connector.subsystems.datasources.AbstractDataSourceService.start(AbstractDataSourceService.java:111)
... 5 more