Thanks to Sbusiso Mkhombe and Karim Deif, because they pointed this out and documented the workaround for the Cloud Shell.
Information in Quarkus
Problem in IBM Cloud Shell
So, in your
cloud-native-starter/reactive directory you need to perform the following tasks:
tar -xvf apache-maven-3.6.3-bin.tar.gz
This should return a message that shows you are using mvn version like 3.6.3
Continue with the execises as usual.
To run the development exercises can you also to setup following tools on your machine:
or check out this Docker image which contains the actual tools.