RFR: bug: no warning shown for parameterized conversions [v5]

[Vicente Romero]

> no warning is shown for parameterized conversions

Vicente Romero has updated the pull request incrementally with two additional commits since the last revision:

 - updating comment
 - refactorings and cleanups to address review comments

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

Changes:
  - all: https://git.openjdk.java.net/valhalla/pull/666/files
  - new: https://git.openjdk.java.net/valhalla/pull/666/files/e75f3089..a2da2108

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=valhalla&pr=666&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=valhalla&pr=666&range=03-04

  Stats: 91 lines in 2 files changed: 31 ins; 34 del; 26 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/666.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/666/head:pull/666

PR: https://git.openjdk.java.net/valhalla/pull/666