Before installing a new Featurepack, I want to be sure that my existing overlays under /apps do not conflict with the updated product code brought by the FeaturePack.
A Package manager enhancement request exists about this problem :
In a future release of the product, the package manager will be able to issue warnings upon installation when it detects that one the files within a package is already overlaid.
Meanwhile, the following workaround is possible :
Using the CQ Package Manager, open the Package page, and use the 'Contents' button to show the package content.
Copy the content into a text file in your file system.
Run the attached shell script with the following arguments :
1) Path of the text file
2) Admin user name of your CQ instance
3) Password of your admin user
4) URL of your CQ instance ("http://localhost:5401") without slash at the end.
The script will check for every overlayable files under /libs in the package, if there is an equivalent file under /apps via a curl request, and output the list of such files.
The merging of the files will then have to be performed manually using standard diff and text tools, in order to adapt the custom code to the updated product code.
Another workaround might be added later, in the form of an integrated JSP in the product that will perform the test.