I would prefer to have a standalone jdt module for this but it just will end up causing module explosion.
Thus putting this in common could work assuming the org.jboss.tools.common.all.feature doesn't include it or at least org.jboss.tools.common.jdt.feature is exposed on its own.
Suggestion is to move it into common/plugins/org.jboss.tools.common.jdt.debug.*
and add a commonfeatures/org.jboss.tools.common.jdt.feature