Test Spring using OpenJ9 with Java 17 support

[sbrannen]

In order to assess potential compatibility issues -- for example, regarding different enforcement of rules specified in the JLS for Java compilers -- we should try building Spring Framework using OpenJ9 once 0.29.1 has been released.

Note from OpenJ9 team: "Java 17 will ship on jdk17.0.1"

• https://github.com/eclipse-openj9/openj9/milestone/32

Downloads from IBM:

• https://developer.ibm.com/languages/java/semeru-runtimes/downloads

[sbrannen]

I tried building main (6.0 M3 snapshots) with OpenJ9 with Java 17 support, but I was unfortunately not aware that OpenJ9 does not support Java Flight Recorder and there are no plans to do so.

See:

• JEP 328 Flight Recorder eclipse-openj9/openj9#1876

The build fails immediately with compiler errors package jdk.jfr does not exist.

In light of that, I am closing this issue since OpenJ9 is currently not an option for building the Spring Framework.

[sbrannen]

Reopening and repurposing this issue to test Spring Framework with OpenJ9's Java 17 support.

We may achieve that with sample applications or potentially by running parts of the test suite with OpenJ9 even though we cannot compile the framework with OpenJ9.