C++ API change report ignores protected API
In preparation of ICU 67 (PR #1070) I noticed that the C++ API change report omitted a protected function (new BasicTimeZone operator=).
Protected functions/fields are still API, so they should be included in the report.
I found that this seems to not be a recent regression. From my email to the team:
Does not show up in https://github.com/unicode-org/icu/blob/maint/maint-56/icu4c/APIChangeReport.html
nor in 58 when the class became stable https://github.com/unicode-org/icu/blob/maint/maint-58/icu4c/APIChangeReport.html
With a quick look for non-@internal protected members (I was too lazy to blame-track internal ones to when they were added) I only saw this API.
It does suggest that protected members not showing up in API change reports is a long-standing issue.