Working through example from this tutorial
Special Notes:
Used homebrew to install opencv, compiled from source to enable java support (as instructed in tutorial)
brew edit opencv
#changed -DBUILD_opencv_java=OFF to -DBUILD_opencv_java=ON
brew install --build-from-source opencv
#For Intellij which is looking for system library: libopencv_java420.dylib
-Djava.library.path=/usr/local/Cellar/opencv/4.2.0_1/share/java/opencv4/