private static StreamSet getStreamSet(String setId, Iterable<InputOperatorSpec> inputOpSpecs, JobGraph jobGraph) {
    Set<StreamEdge> streamEdges = new HashSet<>();
    for (InputOperatorSpec inputOpSpec : inputOpSpecs) {
      StreamEdge streamEdge = jobGraph.getStreamEdge(inputOpSpec.getStreamId());
      streamEdges.add(streamEdge);
    }
    return new StreamSet(setId, streamEdges);
  }
Creates a {@link StreamSet} whose Id is {@code setId}, and {@link StreamEdge}s
correspond to the provided {@code inputOpSpecs}.
samza-core/src/main/java/org/apache/samza/execution/ExecutionPlanner.java