[code-reflection] RFR: OnnxProtoBuilder simplifications [v2]

[Adam Sotona]

> OnnxProtoBuilder simplifications

Adam Sotona has updated the pull request incrementally with one additional commit since the last revision:

  OnnxProtoBuilder refactored

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

Changes:
  - all: https://git.openjdk.org/babylon/pull/324/files
  - new: https://git.openjdk.org/babylon/pull/324/files/c9fc62cb..6bb2c106

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=324&range=01
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=324&range=00-01

  Stats: 92 lines in 3 files changed: 39 ins; 39 del; 14 mod
  Patch: https://git.openjdk.org/babylon/pull/324.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/324/head:pull/324

PR: https://git.openjdk.org/babylon/pull/324