docs: public String getIndexPatternOlderThanDays(String prefix, int days) {
  		// select all indices, then exclude months and days that are not older than the days parameter
  		// Example:
  		// stagemonitor-metrics-*,-stagemonitor-metrics-2015.10.*,-stagemonitor-metrics-2015.09.30
  		final StringBuilder indexPattern = new StringBuilder(prefix).append('*');
  
  		final GregorianCalendar now = getNowUTC();
  		final GregorianCalendar lastDayToExclude = getLastDayToExclude(days);
  		final GregorianCalendar alreadyExcluded = getNowUTC();
  
  		excludeMonths(prefix, now, indexPattern, lastDayToExclude, alreadyExcluded);
  		excludeDays(prefix, indexPattern, lastDayToExclude, alreadyExcluded);
  
  		return indexPattern.toString();
  	}