This issue has been identified during code review for JDK-8218682 and JDK-8198411.

Sergey Bylokhov's comments:
Are we sure that the usage of IndexColorModel is not a bug?

I was able to get IndexColorModel on my desktop by something like this:

User1:
 - sleep for 10 sec - > run java program -> print color model for the current GC -> pause
 - win+L
User2:
 - Login to User2 -> wait 10 sec
User1:
 - IndexColorModel will be printed, instead of DirectColorModel.

So this case requires more investigation.

http://mail.openjdk.java.net/pipermail/2d-dev/2019-February/009861.html
http://mail.openjdk.java.net/pipermail/2d-dev/2019-February/009866.html