The javax packages are generally not automatically exposed by the OSGi framework from the JRE. This allows multiple implementations and versions of these packages to co-exist in the OSGi framework. I know Equinox does expose these packages by default in some configurations.
You can get an OSGi framework to export additional packages from the system bundle by adding them to the org.osgi.framework.system.packages.extra property. In the JBoss OSGi framework this is done by modifying the runtime/server/<configuration>/conf/jboss-osgi-framework.properties file like this:
org.osgi.framework.system.packages.extra=\ javax.sql;version=1.0, \ javax.sql.rowset;version=1.0, \ ... etc ...
Hope this helps,