@VisibleForTesting
  StreamMetadataCache getStreamCache(SystemAdmins admins, Clock clock) {
    if (streamCache == null) {
      streamCache = new StreamMetadataCache(admins, 5000, clock);
    }
    return streamCache;
  }
Shared cache across all KafkaRestoreManagers for the Kafka topic

@param admins system admins used the fetch the stream metadata
@param clock for cache invalidation
@return StreamMetadataCache containing the stream metadata
samza-core/src/main/java/org/apache/samza/storage/KafkaChangelogStateBackendFactory.java