The document writes:
The calculation rolls around the start of the year from Monday to Sunday.
Why does it use "year"?
I also found in plus() it's
The calculation rolls around the end of the week from Sunday to Monday.
And in java.time.Month, both minus() and plus() uses "year".
This is reported in JDK-8326158 and confirmed to be a typo. Now fixed in JDK23 ea