git - heroku doesn't update submodules after push -

i have app hosted on heroku contaiting submodule. submodule contains multiple submodules. submodules in form of http address github repo.

app  |- submodule1  |- other dirs  submodule1  |- submodule2  |- submodule3  |- other dirs 

i made changes in several sobmodules commited (including submodules) , pushed github. can verify, submodules point correct commits i.e. repo may obtained via git clone --recursive ....

after pushed github, pushed heroku. app updated, nevertheless submodules remained same (even though commited , pushed github)!

example of .gitmodules:

[submodule "src/main/java/runtime"]     path = src/main/java/runtime     url = https://github.com/user/repo.git 

what should do? serious problem me.

git treats submodule separate repository regard pushing remote. correct procedure here push each submodule, push submodule containing submodules, , push root project. want this:

cd app/submodule1/submodule2/ git commit -m                  # commit files in submodule2 git push                       # push repository  ...                            # same other submodules in submodule1  cd app/submodule1/ git commit -m                  # commit files in submodule1 git push                       # push repository 

and finally:

cd app/                        # change directory of main project git commit -m                  # commit files in main project git push                       # after date