public Set<String> allDynamicMemberIds() {
        Set<String> dynamicMemberSet = new HashSet<>(allMemberIds());
        staticMembers.values().forEach(dynamicMemberSet::remove);
        return dynamicMemberSet;
    }
@return the ids of all static members in the group.
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/classic/ClassicGroup.java