code: public static final ReadableInterval getReadableInterval(ReadableInterval interval) {
          if (interval == null) {
              long now = DateTimeUtils.currentTimeMillis();
              interval = new Interval(now, now);
          }
          return interval;
      }
docs: Gets the interval handling null.
  <p>
  If the interval is <code>null</code>, an interval representing now
  to now in the {@link ISOChronology#getInstance() ISOChronology}
  will be returned. Otherwise, the interval specified is returned.
  
  @param interval  the interval to use, null means now to now
  @return the interval, never null
  @since 1.1