code: public final String formatStart(Format format) {
          if (format != null) {
              Long minStart = interval.getMinStart();
              if (minStart != null) {
                  return format.format(minStart);
              } else {
                  return null;
              }
          } else {
              Long minStart = interval.getMinStart();
              if (minStart != null) {
                  return numberFormat.get().format(minStart);
              } else {
                  return null;
              }
          }
      }
docs: Uses the given <code>Format</code> to format the start of this
  parameter's interval.
  
  @param format a <code>Format</code> object.
  @return the start of this parameter's interval as a formatted
  <code>String</code>.