RFR: 7409: Update the spotless maven plug-in

[Marcus Hirt]

Modifier order cleanup amazingly enough not yet supported by Eclipse:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=322494

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Commit messages:
 - 7409: Update the spotless maven plug-in

Changes: https://git.openjdk.java.net/jmc/pull/312/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=312&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-7409
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jmc/pull/312.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/312/head:pull/312

PR: https://git.openjdk.java.net/jmc/pull/312