code: @Override
  	public boolean isValid() {
  		boolean mustNotCache =
  				has("Pragma", "no-cache", this.response)
  				|| has("Cache-Control", "no-cache", this.response);
  
  		if (mustNotCache)
  			return false;
  
  		Date now = new Date();
  		Date cacheControl = getCacheControlExpiresDate();
  		Date expires = getExpiresDate();
  
  		return now.before(cacheControl) || now.before(expires);
  	}
docs: /* (non-Javadoc)
  @see com.gistlabs.mechanize.cache.InMemoryCacheEntry#isValid()