you may have openjdk 8 installed but you are still using java 11.
you may have to run this comand also:
sudo update-alternatives --set java /usr/lib/jvm/jdk1.8.0_version/bin/java
check this guide:
you may have openjdk 8 installed but you are still using java 11.
you may have to run this comand also:
sudo update-alternatives --set java /usr/lib/jvm/jdk1.8.0_version/bin/java
check this guide: