Since it is not practical to pre-package everything required to run the material here at GitHub, there are some preparations required before starting the Tutorial. You will need to have a JDK 11 or ...

OpenJDK project teams will focus work on features such as value types, code reflection, AOT compilation, and structured ...

For details of how to build Eclipse OpenJ9 see https://github.com/eclipse-openj9/openj9/tree/master/doc/build-instructions.