code: private void setChaining(Map<Integer, byte[]> hashes, List<Map<Integer, byte[]>> legacyHashes, Map<Integer, List<Tuple2<byte[], byte[]>>> chainedOperatorHashes) {
  		for (Integer sourceNodeId : streamGraph.getSourceIDs()) {
  			createChain(sourceNodeId, sourceNodeId, hashes, legacyHashes, 0, chainedOperatorHashes);
  		}
  	}
docs: Sets up task chains from the source {@link StreamNode} instances.
  
  <p>This will recursively create all {@link JobVertex} instances.