Heroku NodeJS Buildpack with Java JDK
A fork of Heroku's Node.js buildpack that also installs a Java JDK.
2014HerokuNode.js
A fork of someone else's buildpack, made for one deployment and not maintained. Heroku's buildpack has moved on a decade since; use the official one.
Same shape of problem as the Python fork, in the other direction: a Node.js application that shells out to a Java tool has nothing to shell out to, because the Node buildpack has no reason to install a JDK.
This fork installs one during the build, so the application can call it at run time.