@Override
  public Map<String, SystemStreamMetadata> getSystemStreamMetadata(Set<String> streamNames) {
    return inMemoryManager.getSystemStreamMetadata(systemName, streamNames);
  }
Fetch metadata from a system for a set of streams.

@param streamNames
         The streams to to fetch metadata for.
@return A map from stream name to SystemStreamMetadata for each stream
        requested in the parameter set.
samza-core/src/main/java/org/apache/samza/system/inmemory/InMemorySystemAdmin.java