java - withWeekOfWeekyear が異なるオフセットを与えるのはなぜですか?

Question

withWeekOfWeekyear を java.time に変換しようとしています。withWeekOfWeekyear と weekOfWeekBasedYear でオフセットが異なる理由がわかりません。

    DateTime dateTimeWeek = new DateTime().withWeekOfWeekyear(1);
    OffsetDateTime offsetDateTimeWeek = OffsetDateTime.now().with(WeekFields.ISO.weekOfWeekBasedYear(), 1);

    DateTime dateTime = new DateTime();
    OffsetDateTime offsetDateTime = OffsetDateTime.now();

    System.out.println(dateTimeWeek); // 2016-01-04T12:20:50.981-05:00
    System.out.println(offsetDateTimeWeek); // 2016-01-04T12:20:51.034-04:00

    System.out.println(dateTime); // 2016-07-18T12:20:51.101-04:00
    System.out.println(offsetDateTime); // 2016-07-18T12:20:51.101-04:00