third_party directory contains code from the third party including vendored modules that need local modifications (e.g. bug fixes or necessary enhancement before they are incorporated and released in the upstream). Every directory must contain LICENSE files.
The vendored node modules still need to be specified in the dependencies. For example, after copying the tree-kill module to this directory and applying necessary local modification, run from the root of this project directory:
$ npm install --save ./third_party/tree-kill
This will update package.json and package-lock.json to point to the local dependency.
Note: We didn't test vendoring platform-dependent modules yet.
tree-kill: