fullstop-plugins/fullstop-save-securitygroups-plugin/src/main/java/org/zalando/stups/fullstop/plugin/PrefixBuilder.java
static String build(final String accountId, final String region, final DateTime instanceLaunchTime) {
        return Paths.get(
                accountId, region, instanceLaunchTime.toString("YYYY"), instanceLaunchTime.toString("MM"),
                instanceLaunchTime.toString("dd")).toString() + "/";
    }
static String build(final String accountId, final String region, final DateTime instanceLaunchTime) {
        return Paths.get(
                accountId, region, instanceLaunchTime.toString("YYYY"), instanceLaunchTime.toString("MM"),
                instanceLaunchTime.toString("dd")).toString() + "/";
    }
Builds the prefix that will be prepended to the 'bucketname'<br/>
Something like '123456789/eu-west-1/2015/06/12/'

@param accountId
@param region             name of region
@param instanceLaunchTime
@return