code: public void setDateLastModifiedToPreviousTimeout(long timeout) {
  
          long now = System.currentTimeMillis();
          long daytime = now % 86400000;
          long timeoutMinutes = timeout * 60000;
          setDateLastModified(now - (daytime % timeoutMinutes));
      }
docs: Sets the "last modified" date for this Flex cache entry by using the last passed timeout value.<p>
  
  If a cache entry uses the timeout feature, it becomes invalid every time the timeout interval
  passes. Thus the "last modified" date is the time the last timeout passed.<p>
  
  @param timeout the timeout value to use to calculate the date last modified