code: public static Minutes standardMinutesIn(ReadablePeriod period) {
          int amount = BaseSingleFieldPeriod.standardPeriodIn(period, DateTimeConstants.MILLIS_PER_MINUTE);
          return Minutes.minutes(amount);
      }
docs: Creates a new <code>Minutes</code> representing the number of complete
  standard length minutes in the specified period.
  <p>
  This factory method converts all fields from the period to minutes using standardised
  durations for each field. Only those fields which have a precise duration in
  the ISO UTC chronology can be converted.
  <ul>
  <li>One week consists of 7 days.
  <li>One day consists of 24 hours.
  <li>One hour consists of 60 minutes.
  <li>One minute consists of 60 seconds.
  <li>One second consists of 1000 milliseconds.
  </ul>
  Months and Years are imprecise and periods containing these values cannot be converted.
  
  @param period  the period to get the number of minutes from, null returns zero
  @return the period in minutes
  @throws IllegalArgumentException if the period contains imprecise duration values