Ability to pass reference repo recursively. Right now we have to do submodule update outside of Git plugin as it does not understand reference repo parameter for the submodules, i.e. if the reference repo is passed to the plugin it is not used when cloning/fetching from the submodules

A work around is to do git command in the build instead of defining it in the Jenkins UI git section. This do not introduce problem except it is error prone.