Same here, though it doesn't seem like they've upgraded fully. The Dockerfile[0] for their Kubernetes base images are pinned at 1.8, for example. I bit the bullet and built Spark against newer JDK's myself in the last couple years, but look forward to ditching that.

The Hadoop ecosystem has definitely been dragging its feet on JDK bumps.

[0] https://github.com/apache/spark/blob/master/resource-manager...