RFR: 7413: Fix building JMC with Docker

[Christoph Dreis]

Hi,

I noticed that the Docker builds still point to JDK 8 and thus fail with messages like the following.


Caused by: java.lang.UnsupportedClassVersionError: org/eclipse/tycho/core/maven/TychoMavenLifecycleParticipant has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0


This PR therefore upgrades the Docker images to newer JDK 11 images, which fixes the issues described.

This would need a ticket in the bug tracker and I hope you can create this for me. OCA should be signed already, but let me know if I need to confirm something again.

In case you think this is worthwhile, I would appreciate it if this is sponsored.

Cheers,
Christoph

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Commit messages:
 - Fix building JMC with Docker

Changes: https://git.openjdk.java.net/jmc/pull/317/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=317&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-7413
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jmc/pull/317.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/317/head:pull/317

PR: https://git.openjdk.java.net/jmc/pull/317