FlowGraphGenerator gen = new FlowGraphGenerator();
gen.defineInput("in");
gen.defineOperator("op1", "in", "out");
gen.defineOperator("op2", "in", "out", FlowBoundary.SHUFFLE);
gen.defineOutput("out");
gen.connect("in", "op1").connect("op1", "op2").connect("op2", "out");
FlowBlock b1 = FlowBlock.fromPorts(
0,
gen.toGraph(),
new ArrayList<FlowElementInput>(gen.inputs("op1")),