Exports from the system bundle are no longer all available to apps, this change came in with Platform 7 and restrictions on “Grey APIs”
A package can be exported by the system bundle, but unavailable for import in apps, this is intentional with Platform 7.
When this happens, you’ll see a warning in the logs telling you.
I recommend reading the hundreds of replies in the threads relating to platform 7, which should get you up to speed.
For dependencies no longer available for import from the platform, you must bundle them within your app, using compile scope. Commons Lang 3 might be exported for apps, this is something you’d need to verify, and then swap usage if so.