[code-reflection] RFR: Method code model uniquness [v3]

[Mourad Abbay]

> Multiple `Method` objects that represent the same java method, have different code models. This is because every time we call `Class.getMethod` or `Class.getDeclaredMethod` we get a newly created instance. One possible solution is to attach the model to the root `Method` object.

Mourad Abbay has updated the pull request incrementally with one additional commit since the last revision:

  Apply Maurizio's suggestion

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Changes:
  - all: https://git.openjdk.org/babylon/pull/415/files
  - new: https://git.openjdk.org/babylon/pull/415/files/f88f4e2b..4c2b662d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=415&range=02
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=415&range=01-02

  Stats: 8 lines in 1 file changed: 4 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/babylon/pull/415.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/415/head:pull/415

PR: https://git.openjdk.org/babylon/pull/415