Checkout@v2 can't recursively checkout submodules with `submodules: true`

In our repo, we have a .gitmodules file:

[submodule "third_party/gossip"]
	path = third_party/gossip
	url =

and gossip also has its own .gitmodules, which should be run to introduce submodules recursively, but it seems Checkout@v2 doesn’t fetch submodules recursively even with submodules: true.
Is it a bug of Checkout@v2? Can anyone give me some hints about how to solving it?

This is the command line used by Checkout@V2:
/usr/bin/git -c protocol.version=2 submodule update --init --force --depth=1
In order to fetch the submodules recursively, I think it’s better to have the --recursive flag, how can I achieve this?

Problem solved by changing submodules: true to submodules: recursive