Optional<PartitionMetadata> partitionMetadata(TopicPartition topicPartition) {
        return Optional.ofNullable(metadataByPartition.get(topicPartition));
    }
An internal immutable snapshot of nodes, topics, and partitions in the Kafka cluster. This keeps an up-to-date Cluster
instance which is optimized for read access.
Prefer to extend MetadataSnapshot's API for internal client usage Vs the public {@link Cluster}
clients/src/main/java/org/apache/kafka/clients/MetadataSnapshot.java