RFR: 8367901: Calendar.roll(hour, 24) returns wrong result [v2]

[Justin Lu]

> Please review this PR which addresses an edge case for `GregorianCalendar.roll(int, int)` when the rolled amount would cause the hour to remain the same as before the call. After this change, the expected hour is returned. That is, rolling a full cycle for HOUR (12 hours) and HOUR_OF_DAY (24 hours) should keep the hour the same as before the call.
> 
> For example, a calendar with HOUR_OF_DAY == 15,
> 
> 
> cal.roll(Calendar.HOUR_OF_DAY, 23);
> cal.get(Calendar.HOUR_OF_DAY); // returns 14
> 
> 
> cal.roll(Calendar.HOUR_OF_DAY, 24);
> // Incorrectly returns 16. A full cycle is expected to return the starting hour (15)
> cal.get(Calendar.HOUR_OF_DAY); 
> 
> 
> cal.roll(Calendar.HOUR_OF_DAY, 25);
> cal.get(Calendar.HOUR_OF_DAY); // returns 16

Justin Lu has updated the pull request incrementally with two additional commits since the last revision:

 -  + - to - in comment
 - DST test cases + compute expected value as method + improve err msg

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27355/files
  - new: https://git.openjdk.org/jdk/pull/27355/files/f214e1db..9316ca62

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27355&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27355&range=00-01

  Stats: 81 lines in 1 file changed: 52 ins; 0 del; 29 mod
  Patch: https://git.openjdk.org/jdk/pull/27355.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27355/head:pull/27355

PR: https://git.openjdk.org/jdk/pull/27355