Run this manual test
java/awt/image/multiresolution/MultiResolutionIcon/MultiResIconTest.java
on OS X. I guess, on macOS as well:-). And also ubuntu Linux (I tried two different, all with failure reported as success)
Use PIT build for jdk9 b141.
It would require title icon (not defined on this system) and a blue task bar icon (wrong, it is standard cup of java icon), and when I press Fail, it would report Passed.

I put there testbug label/summary tag but please evaluate if there's no product issue as well.
UPDATE: and there most probably is -- I have the test always failing on two different Ubuntu Linuxes: task bar icon is always green.