@Override
    public String toString() {
        return "MemberSubscriptionAndAssignmentImpl(rackId=" + rackId.orElse("N/A") +
            ", instanceId=" + instanceId +
            ", subscribedTopicIds=" + subscribedTopicIds +
            ", memberAssignment=" + memberAssignment +
            ')';
    }
Constructs a new {@code MemberSubscriptionAndAssignmentImpl}.

@param rackId                The rack Id.
@param subscribedTopicIds    The set of subscribed topic Ids.
@param memberAssignment      The current member assignment.
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/modern/MemberSubscriptionAndAssignmentImpl.java