@Override
    public String toString() {
        return "(memberId=" + memberId +
            ", groupInstanceId=" + groupInstanceId.orElse("null") +
            ", clientId=" + clientId +
            ", host=" + host +
            ", assignment=" + assignment +
            ", targetAssignment=" + targetAssignment + ")";
    }
The target assignment of the member. Provided only for consumer group.
clients/src/main/java/org/apache/kafka/clients/admin/MemberDescription.java