Expected: Prints "standard", "search", "emoji", "eor".
Actual: Prints "<null>" four times.
To workaround this issue, I've added `ulist_resetList(values);` add the end of `KeywordsSink#put(...)` in source/i18n/collation.cpp (the UList's `curr` pointer is a nullptr, which means `ulist_getNext` also returns nullptr instead of enumerating the list's values).
This is a regression starting with ICU 58.
GitHub ID: anba