Plug-in

How to debug Indesign plugin source code in Xcode?

inexutils — InDesign plugin to ignore missing plugins information from documents (by Manan-Joshi)

KohakuExtendScriptStyleShortcut — a plugin that extends the script for adding shortcut properties to styles by Kohaku Nekotarou
The build method is also clearly documented, so if you're interested, please try developing plugins in C++.