This subdirectory contains the KDevelop Platform Libraries, a set of libraries used to create plugins for KDevelop or other IDEs based on kdevplatform.
The idea that this subdirectory contains
- Everything to create platform plugins
- Everything to create platform applications
- Commonly used/important plugins (e.g. VCS plugins)
API documentation is available from: https://api.kde.org/extragear-api/kdevelop-apidocs/kdevelop/kdevplatform/html/index.html