Display files which caused CI cache to rebuild
Cache (ideally) should not change on building the same commit (or subsequent commit without changes in source code and build configuration). This would eliminate time (and resources) needed to build and upload modified cache tarball/zip.
Currently it's very hard to determine which (cacheable) files changed to tune up build/CI configuration if a build system (such as Gradle) mixes downloaded artifacts with metadata regarding its up-to-date check time in the same directory.
A list of changed files (which caused a cache to rebuild) should be displayed before the "Uploading cache.zip to ..." message. This list should be probably limited to X positions to do not clutter the output (yet to allow to remove the problem by using
after_script to remove offending - often changing - files).
That solution is already used among others by Travis CI.