[jdk17] RFR: JDK-8269150 Unicode \u005C not treated as an escaping backslash [v4]

[Jim Laskey]

> \u005C Unicode escape sequence not being treated as a backslash for general escape sequences.

Jim Laskey has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Merge branch 'master' into 8269150
 - Updated the test to include all combinations
 - Merge branch 'master' into 8269150
 - Correct unicode escape handling in UnicodeReader, added test

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

Changes:
  - all: https://git.openjdk.java.net/jdk17/pull/126/files
  - new: https://git.openjdk.java.net/jdk17/pull/126/files/3e2886d6..8c5f1acd

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk17&pr=126&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk17&pr=126&range=02-03

  Stats: 10172 lines in 284 files changed: 7600 ins; 1274 del; 1298 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/126.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/126/head:pull/126

PR: https://git.openjdk.java.net/jdk17/pull/126