public static int minutesInHourOf(long duration) {
        return (int) (duration - hoursOf(duration) * MILLIS_PER_HOUR) / MILLIS_PER_MINUTE;
    }
Calculates the number of minutes within the specified duration excluding full hours.

@param duration duration in milliseconds
@return number of minutes within the specified duration.
android/third_party/time-duration-picker/src/main/java/mobi/upod/timedurationpicker/TimeDurationUtil.java