[code-reflection] Integrated: After previous linux (clang tidy) changes, mac c++ wanted a few tweaks

[Gary Frost]

Mac c++/clang compiler fussed over lack of <sstream> and inconsistant use of 'override'

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Commit messages:
 - After previous linux (clang tidy) changes, mac c++ wanted a few tweaks

Changes: https://git.openjdk.org/babylon/pull/452/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=452&range=00
  Stats: 2 lines in 2 files changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/babylon/pull/452.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/452/head:pull/452

PR: https://git.openjdk.org/babylon/pull/452