why using millisecond ClockSource on macOs

[microhardsmith]

in com.zaxxer.hikari.util.ClockSource.Factory, only MacOS will use MillisecondClockSource(), maybe in consideration of MacOS nanotime not precise issue, but I think jdk should have fixed that, the code was commited in 2015, perhaps I am not getting the point, could you guys check this out please.