docs: static int countInPeriod(Weekday dow, Weekday dow0, int nDays) {
          // Two cases
          //    (1a) dow >= dow0: count === (nDays - (dow - dow0)) / 7
          //    (1b) dow < dow0:  count === (nDays - (7 - dow0 - dow)) / 7
          if (dow.javaDayNum >= dow0.javaDayNum) {
              return 1 + ((nDays - (dow.javaDayNum - dow0.javaDayNum) - 1) / 7);
          } else {
              return 1 + ((nDays - (7 - (dow0.javaDayNum - dow.javaDayNum)) - 1) / 7);
          }
      }