RFR: Addressing TODOs

[Alexandre Iline]

This completes the work on CODETOOLS-7903274.
Remaining are updates to data coverage plugin.

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Commit messages:
 - Addressing TODOs

Changes: https://git.openjdk.org/jcov/pull/38/files
 Webrev: https://webrevs.openjdk.org/?repo=jcov&pr=38&range=00
  Stats: 963 lines in 20 files changed: 628 ins; 292 del; 43 mod
  Patch: https://git.openjdk.org/jcov/pull/38.diff
  Fetch: git fetch https://git.openjdk.org/jcov pull/38/head:pull/38

PR: https://git.openjdk.org/jcov/pull/38