private Stream<SystemStreamPartition> mapSSMToSSP(Map.Entry<SystemStream, SystemStreamMetadata> ssMs) {
    return ssMs.getValue()
        .getSystemStreamPartitionMetadata()
        .keySet()
        .stream()
        .map(partition -> new SystemStreamPartition(ssMs.getKey(), partition));
  }
For each input stream specified in config, exactly determine its
partitions, returning a set of SystemStreamPartitions containing them all.
samza-azure/src/main/java/org/apache/samza/coordinator/AzureJobCoordinator.java