I dug out a J310 and did a youtube video just for you.
That appears to be one of those rare Adobe only videos which are unable to view on this PC but I'll assume you demonstrated functionality. Congratulations, forum record holder for simplest oscillator. I'll have to be satisfied with smallest and el-cheapoest ATM.
Interestingly no hint of that circuit in first couple hundred images with google "simplest oscillator" so looks like you are the world record holder too. Or maybe not because "reichsflugtransistor" came up with dozens of references to either nazi oppression or n-channel this morning, then an hour ago couple for mouser/digikey, and now... only this post. So something funny is afoot with my cookies or the search engine.
I'm impressed and almost tempted to order some J310 parts. But first further experiments with the PN4117. I'm wondering if it might have something to do with slight difference in Vgs(f). Mine draws almost nothing with gate grounded but J310 probably some microamps. Most other specs similar including picofarads. Not much info on top frequency for either.
Anyway thanks for the effort. You have definitely aroused my interest in this amazing circuit.