public void add(TopicPartition topicPartition, PartitionData data) {
            next.put(topicPartition, data);
            // topicIds should not change between adding partitions and building, so we can use putIfAbsent
            if (data.topicId.equals(Uuid.ZERO_UUID)) {
                partitionsWithoutTopicIds++;
            } else {
                topicNames.putIfAbsent(data.topicId, topicPartition.topic());
            }
        }
Mark that we want data from this partition in the upcoming fetch.
clients/src/main/java/org/apache/kafka/clients/FetchSessionHandler.java