* {@link FlowBlock#isSucceedingReduceBlock()}
*/
@Test
public void isSucceedingReduceBlock_empty() {
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");