public void setStartDateTime(java.util.Date startDateTime) {
        this.startDateTime = startDateTime;
    }
<p>
The date/time the instance group was started.
</p>

@param startDateTime
       The date/time the instance group was started.
aws-java-sdk-emr/src/main/java/com/amazonaws/services/elasticmapreduce/model/InstanceGroupDetail.java