This doesn’t draw the line exactly where the method changed from private to public, but generally speaking:
– gson-2.2.4.jar: the method is private, and therefore too old for use here
– gson-2.6.1: the method is public, and works fine.
– Somewhere between the two, the method’s status changed.
So, because I had some functionality that required the method be public and accessible, it was important I specify the right version in my dependency manager (SBT). “That’s easy,” I thought. “No problem.”
Spoilers: there was a problem.