Oracle JDK 11 (and 10) are pre-installed, not the OpenJDK builds

Sorry for the delay of my reply as well, @louise-davies!

It seems this line

source ~/.bash_profile

is changing the default Java version from openjdk version "1.8.0_181" to openjdk version "11.0.1" 2018-10-16.

Could you tell us why you are sourcing .bash_profile there?

Thanks!