code: @Override
      public Long getMinimumLength() {
          calculator();
          if (simple) {
              return v[2] - v[1];
          } else {
              Weight minDur = cn.getMinimumDuration();
              return minDur.isInfinity() ? null : minDur.value();
          }
      }
docs: /*
  (non-Javadoc)
  
  @see org.virginia.pbhs.parameters.Interval#getMinimumDuration()