Installed Ubuntu20 using rockpi4c install instructions.
Using non-source install instructions for OpenCV:
I get this on the last instruction:
sudo apt-get install opencv4.0
Reading package lists… Done
Building dependency tree
Reading state information… Done
Note, selecting ‘libopencv4.0-java’ for regex ‘opencv4.0’
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
The opencv test then fails.