[code-reflection] Integrated: Ensure array attributes are serialized correctly

[Paul Sandoz]

Operation attributes that are instances of arrays are not serialized correctly, Array::toString prints out the object identity and not the contents.

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Commit messages:
 - Ensure array attributes are serialized correctly.

Changes: https://git.openjdk.org/babylon/pull/310/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=310&range=00
  Stats: 133 lines in 2 files changed: 125 ins; 3 del; 5 mod
  Patch: https://git.openjdk.org/babylon/pull/310.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/310/head:pull/310

PR: https://git.openjdk.org/babylon/pull/310