code: public static Duration standardMinutes(long minutes) {
          if (minutes == 0) {
              return ZERO;
          }
          return new Duration(FieldUtils.safeMultiply(minutes, DateTimeConstants.MILLIS_PER_MINUTE));
      }
docs: Create a duration with the specified number of minutes assuming that
  there are the standard number of milliseconds in a minute.
  <p>
  This method assumes that there are 60 seconds in a minute and
  1000 milliseconds in a second.
  All currently supplied chronologies use this definition.
  <p>
  A Duration is a representation of an amount of time. If you want to express
  the concept of 'minutes' you should consider using the {@link Minutes} class.
  
  @param minutes  the number of standard minutes in this duration
  @return the duration, never null
  @throws ArithmeticException if the minutes value is too large
  @since 1.6