NullPointerException occurs if S3 bucket has no expiration policy

https://github.com/aodn/aws-wps/blob/master/wps-common/src/main/java/au/org/aodn/aws/util/S3Utils.java#L138

java.lang.NullPointerException
08:09:41
at au.org.aodn.aws.util.S3Utils.getExpirationinDays(S3Utils.java:138)