RFR: 7526: JMC not buildable with jdk17 [v5]

[Johannes Bechberger]

> Tested on Java 11 x86 and aarch64 (azul, but only builds), and on Java 17 x86 and aarch64.

Johannes Bechberger has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Add JDK 17 to CI
 - Fix --add-exports
   
   Multiple --add-exports seem to require a flag like -version
   in between.
   It maybe related to https://bugs.eclipse.org/bugs/show_bug.cgi?id=544016
 - Update p2-maven-plugin
 - Bump mockito to run --installCore on JDK 17

-------------

Changes:
  - all: https://git.openjdk.java.net/jmc/pull/363/files
  - new: https://git.openjdk.java.net/jmc/pull/363/files/639c4575..019a32d3

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmc&pr=363&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=jmc&pr=363&range=03-04

  Stats: 139 lines in 12 files changed: 10 ins; 84 del; 45 mod
  Patch: https://git.openjdk.java.net/jmc/pull/363.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/363/head:pull/363

PR: https://git.openjdk.java.net/jmc/pull/363