I installed Catalina beta (the latest macOS version) and the getImage() hang seems to be back. Again, it seems like a permissions issue, but sexscripts/java isn't causing the OS to prompt for camera permission for some reason. There's also a report about it at webcam-capture on GitHub (
https://github.com/sarxos/webcam-capture/issues/723). It looks like they were potentially able to solve it by switching drivers.
Catalina is currently in beta, and hasn't been released. Hopefully this will be ironed out before the final release date, but I wanted to give everyone a heads-up that it may be an issue again. If anyone has success with Catalina or can figure out a work-around, please let us all know!