public void setUserIds(java.util.Collection<String> userIds) {
        if (userIds == null) {
            this.userIds = null;
            return;
        }

        this.userIds = new com.amazonaws.internal.SdkInternalList<String>(userIds);
    }
<p>
The list of user IDs that belong to the user group.
</p>

@param userIds
       The list of user IDs that belong to the user group.
aws-java-sdk-elasticache/src/main/java/com/amazonaws/services/elasticache/model/UserGroup.java