I ran into the same issue after running brew upgrade.
For me the solution was to install official JDK 11, not brew's openjdk. No matter what I tried, I couldn't get neoj4 to recognize that I have openjdk@11 via brew installed.
https://www.oracle.com/java/technologies/javase-downloads.html
To see which versions of jdk you have installed, try running
ls -la /Library/Java/JavaVirtualMachines/
you should see something like
ls -la /Library/Java/JavaVirtualMachines/ 2126ms Thu Jul 9 18:30:19 2020
total 0
drwxr-xr-x 5 root wheel 160 Jul 9 18:30 ./
drwxr-xr-x 5 root wheel 160 Jun 1 14:34 ../
drwxr-xr-x 3 root wheel 96 Jul 9 18:29 jdk-11.0.7.jdk/
drwxr-xr-x 3 root wheel 96 Jul 9 18:30 jdk-14.0.1.jdk/
drwxr-xr-x 3 root wheel 96 Oct 1 2018 jdk1.8.0_181.jdk/