Buildpack error attempting to upgrade to 0.25 on Heroku


I’m attempting to upgrade my Heroku deployment to 0.25 following the instructions in the docs, but when I attempt to push master to heroku, it is being rejected by the buildpack:

$ src git clone
Cloning into 'metabase-deploy'...
remote: Counting objects: 411, done.
remote: Total 411 (delta 0), reused 0 (delta 0), pack-reused 411
Receiving objects: 100% (411/411), 1.06 GiB | 4.42 MiB/s, done.
Resolving deltas: 100% (182/182), done.
Checking connectivity... done.

$ cd metabase-deploy
$ git remote add heroku[my-metabase-app].git
$ heroku buildpacks:add
Buildpack added. Next release on [my-metabase-app] will use:
Run git push heroku master to create a new release using these buildpacks.
$ git push -f heroku master
Counting objects: 31, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (15/15), done.
Writing objects: 100% (31/31), 4.19 KiB | 0 bytes/s, done.
Total 31 (delta 17), reused 30 (delta 16)
remote: Compressing source files... done.
remote: Building source:
remote: -----> JVM Common app detected
remote: -----> Installing OpenJDK 1.8... done
remote: -----> Failed to detect app matching buildpack
remote:        More info:
remote:  !     Push failed
remote: Verifying deploy...
remote: !	Push rejected to /[my-metabase-app].
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to '[my-metabase-app].git'

Has anyone been able to do this?