[code-reflection] Integrated: Replace string literals with class names with references to Class apis

[Gary Frost]

We had a few references to class names as String literals, I replaced with Class.getSimpleName() so that we can safely refactor code (rename classes).

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Commit messages:
 - Replace string literals with class names with references to Class apis

Changes: https://git.openjdk.org/babylon/pull/719/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=719&range=00
  Stats: 7 lines in 3 files changed: 1 ins; 2 del; 4 mod
  Patch: https://git.openjdk.org/babylon/pull/719.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/719/head:pull/719

PR: https://git.openjdk.org/babylon/pull/719