private void updateStaticMember(ConsumerGroupMember newMember) {
        if (newMember.instanceId() != null) {
            staticMembers.put(newMember.instanceId(), newMember.memberId());
        }
    }
Updates the member id stored against the instance id if the member is a static member.

@param newMember The new member state.
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/modern/consumer/ConsumerGroup.java