How to force Spotlight to index content inside a package?

I wish to use Spotlight to search inside my Papers 3 library package (i.e., a 'bundle') as the search functionality within the application is broken and/or hamstrung. Is there any way I can force Spotlight to index the contents of the PDFs in this package?

I've tried EasyFind as an alternative and it seems pretty useless at searching file contents.

Solution 1:

Not a direct solution to this problem, per se, but a workaround: the (very expensive) software FoxTrot Professional Search finds files within bundles like the one used by Papers 3. It's very flexible and powerful for searching document contents in its own right, too.