@Override
        public final ApiResult<K, V> handleResponse(Node broker, Set<K> keys, AbstractResponse response) {
            if (keys.size() != 1) {
                throw new IllegalArgumentException("Unbatched admin handler should only be required to handle responses for a single key at a time");
            }
            K key = keys.iterator().next();
            return handleSingleResponse(broker, key, response);
        }
An {@link AdminApiHandler} that will create one request per key, not performing any grouping based
on the targeted broker. This type of handler should only be used for broker APIs that do not accept
multiple keys at once, such as initializing a transactional producer.
clients/src/main/java/org/apache/kafka/clients/admin/internals/AdminApiHandler.java