From the IRC:
The early access versions for macOS does not seem to work. Downloaded installer DMG from (http://jdk.java.net/jmc/) and when I run the PKG installer all seems to go well, but nothing is created in /Applications. When I unpack the jmc-7.0.0-ea+04_osx-x64_bin.tar.gz and double-click it, I get a warning from macOS about "“jmc-7.0.0-ea+04_osx-x64_bin.app” is damaged and can’t be opened. You should move it to the Trash.". Manually starting works, so this is looks like some Gatekeeper issue with the tar.gz version. Has anyone tried these on macOS?