mContentTitle is not public in Builder; cannot be accessed from outside package

Some background:

I’ve inherited a VR project for Daydream/Gear, and the previous team had been running a modified version of UE4.16 with GoogleVR 1.6 integration, mostly to add a few functionalities that UE could not do. One of the modifications they had also done was to modify packaging to use gradle instead of Ant. As UE has their own implementation of gradle starting in 4.17, I decided best to try to use that from now on. I am still new to this however, and while I managed to figure out most of the issues so far, this one seems to have me stuck.


UATHelper: Packaging (Android (ETC2)): Z:\app\src\main\java\com\google\android\vending\expansion\downloader\impl\ error: mContentTitle is not public in Builder; cannot be accessed from outside package
UATHelper: Packaging (Android (ETC2)):         expandedView.setTextViewText(, mContentTitle);
UATHelper: Packaging (Android (ETC2)):                                                  ^

As far as I can tell, it’s trying to access mContentTitle from NotificationCompat.Builder, which, I believe comes from

In our APK/gradle/app/build.gradle file, we have

compile ''

This however does not seem to cause issues in our 4.16 version, and NotificationCompat.Builder  |  Android Developers appears to indicate there is no mContentTitle attribute that is publically available.
It also seems that the offending line is present from the 4.16 version through to the 4.18 version, including the versions downloaded from Epic’s Game Launcher (yet attempting to package an example project did not cause issue, so evidently there is something about our version that is amiss).

Ultimately, I’m attempting to transition from all the manual modifications of the previous team to the nice programmatic approach that Epic took, but it’s giving me plenty of headaches.