SU* keys in plist files
Solution 1:
Sparkle
These keys are used by the open source Sparkle framework.
Sparkle is an easy-to-use software update framework for macOS applications. It delivers updates using appcasting, a term used to refer to the practice of using RSS to distribute update information and release notes.
SU stands for Software Update. The project publishes documentation for currently supported property list (plist) keys.