How to handle git sources with submodules?

HI again apologize if this is a stupid question, I am still learning and I haven't found an answer to this in the forum.

How can I gracefully handle git sources that depend on sub modules?

say per example this:

GitHub - GStreamer/gst-plugins-base: 'Base' GStreamer plugins and helper libraries

It has a submodule called "common" if I create a simple package.mk that pulls the latest hash the compilation fails complaining that I need the sub module.

I have been dealing with it like this:

post_unpack() {
  rm -rf $BUILD/$PKG_NAME-*/
  git clone https://github.com/GStreamer/gst-plugins-base $BUILD/$PKG_NAME-$PKG_VERSION/
  cd $BUILD/$PKG_NAME-$PKG_VERSION/
  git checkout $PKG_VERSION
  git submodule update --init
  cd $ROOT
}

But I am not sure if this is the right way to do it since every time I have to recompile because of any change, it clones the repo again, instead of just getting it from the source folder.

also I am not 100% positive but it seems this also breaks compilation on some libraries.

Quote from vpeter

Make another package as dependency which doesn't build anything. It just unpack sources. And you can use them from original package.

Thanks for the reply, unfortunately I don't think I follow.

What I understand is, create a package that points to the "commom" sub module and then add it as a dependency? do this for all required sub modules?

Is there an example anywhere I could check ?