public KafkaFuture<Collection<Throwable>> errors() {
        return errors;
    }
Returns a future which yields just the errors which occurred.

If this future yields a non-empty collection, it is very likely that elements are
missing from the valid() set.

This future itself never fails with an error.  In the event of an error, this future
will successfully yield a collection containing at least one exception.
clients/src/main/java/org/apache/kafka/clients/admin/ListConsumerGroupsResult.java