Cannot add custom modules to WildFly Swarm using <resource-root> instead of <artifact> in the module.xml

JDBC drivers (DB2, Oracle, etc) not available to WildFly Swarm when added as modules (like in WildFly/EAP) using <resource-root> instead of <artifact> in the module.xml.

Custom module "oracle.jdbc" (module.xml and JAR) copied into Uber-JAR's "modules\oracle\jdbc\main" directory (there are also some default modules there - jboss, javax, etc) when module is configured like this:

   <resources>
      <resource-root path="oracle-driver-ojdbc6.jar"/>
   </resources>

However, when running app (driver and datasource configured in the standalone.xml), I'm getting this error:

[jboss.as.connector.subsystems.datasources] (ServerService Thread Pool -- 21) WFLYJCA0086: Unable to find driver class name in "oracle" jar

However, when it is configured in module.xml as:

      <artifact name="com.hynnet:oracle-driver-ojdbc6:12.1.0.1"/>

JAR is copied to "m2repo\com\hynnet\oracle-driver-ojdbc6\12.1.0.1" directory of Uber-JAR and driver was successfully loaded.

Looks like WFS adding to classpath only what is in "m2repo", but not the "oracle" module in "modules" directory.
Am I missing some command-line parameter to define location of the custom modules, like "JBOSS_MODULEPATH" for JBoss EAP6?