public RetentionPeriod withRetentionPeriodUnit(RetentionPeriodUnit retentionPeriodUnit) {
        this.retentionPeriodUnit = retentionPeriodUnit.toString();
        return this;
    }
<p>
The unit of time in which the retention period is measured. Currently, only <code>DAYS</code> is supported.
</p>

@param retentionPeriodUnit
       The unit of time in which the retention period is measured. Currently, only <code>DAYS</code> is
       supported.
@return Returns a reference to this object so that method calls can be chained together.
@see RetentionPeriodUnit
aws-java-sdk-recyclebin/src/main/java/com/amazonaws/services/recyclebin/model/RetentionPeriod.java