Code review comment: Same as above. Sorry that I forget to rewind this when I rewind the merging of FLINK-21328 and FLINK-21330.

Code before review:
public void returnsIncidentBlockingPartitions() throws Exception {
final JobVertex a = ExecutionGraphTestUtils.createNoOpVertex(1);
final JobVertex b = ExecutionGraphTestUtils.createNoOpVertex(1);
final JobVertex c = ExecutionGraphTestUtils.createNoOpVertex(1);
final JobVertex d = ExecutionGraphTestUtils.createNoOpVertex(1);
final JobVertex e = ExecutionGraphTestUtils.createNoOpVertex(1);
b.connectNewDataSetAsInput(a, DistributionPattern.POINTWISE, ResultPartitionType.BLOCKING);
c.connectNewDataSetAsInput(b, DistributionPattern.POINTWISE, ResultPartitionType.PIPELINED);
d.connectNewDataSetAsInput(b, DistributionPattern.POINTWISE, ResultPartitionType.PIPELINED);
e.connectNewDataSetAsInput(c, DistributionPattern.POINTWISE, ResultPartitionType.BLOCKING);
e.connectNewDataSetAsInput(d, DistributionPattern.POINTWISE, ResultPartitionType.PIPELINED);
final DefaultExecutionGraph simpleTestGraph =
ExecutionGraphTestUtils.createSimpleTestGraph(a, b, c, d, e);
final DefaultExecutionTopology topology =
DefaultExecutionTopology.fromExecutionGraph(simpleTestGraph);
final DefaultSchedulingPipelinedRegion firstPipelinedRegion =
topology.getPipelinedRegionOfVertex(new ExecutionVertexID(a.getID(), 0));
final DefaultSchedulingPipelinedRegion secondPipelinedRegion =
topology.getPipelinedRegionOfVertex(new ExecutionVertexID(e.getID(), 0));
final DefaultExecutionVertex vertexB0 =
topology.getVertex(new ExecutionVertexID(b.getID(), 0));
final IntermediateResultPartitionID b0ConsumedResultPartition =
Iterables.getOnlyElement(vertexB0.getConsumerPartitionGroups().get(0));
final Set<IntermediateResultPartitionID> secondPipelinedRegionConsumedResults =
IterableUtils.toStream(secondPipelinedRegion.getConsumedResults())
.map(DefaultResultPartition::getId)
.collect(Collectors.toSet());
assertThat(firstPipelinedRegion.getConsumedResults().iterator().hasNext(), is(false));
assertThat(secondPipelinedRegionConsumedResults, contains(b0ConsumedResultPartition));
}

Line under review: Iterables.getOnlyElement(vertexB0.getConsumerPartitionGroups().get(0));

Code after addressing the review:
public void returnsIncidentBlockingPartitions() throws Exception {
final JobVertex a = ExecutionGraphTestUtils.createNoOpVertex(1);
final JobVertex b = ExecutionGraphTestUtils.createNoOpVertex(1);
final JobVertex c = ExecutionGraphTestUtils.createNoOpVertex(1);
final JobVertex d = ExecutionGraphTestUtils.createNoOpVertex(1);
final JobVertex e = ExecutionGraphTestUtils.createNoOpVertex(1);
b.connectNewDataSetAsInput(a, DistributionPattern.POINTWISE, ResultPartitionType.BLOCKING);
c.connectNewDataSetAsInput(b, DistributionPattern.POINTWISE, ResultPartitionType.PIPELINED);
d.connectNewDataSetAsInput(b, DistributionPattern.POINTWISE, ResultPartitionType.PIPELINED);
e.connectNewDataSetAsInput(c, DistributionPattern.POINTWISE, ResultPartitionType.BLOCKING);
e.connectNewDataSetAsInput(d, DistributionPattern.POINTWISE, ResultPartitionType.PIPELINED);
final DefaultExecutionGraph simpleTestGraph =
ExecutionGraphTestUtils.createSimpleTestGraph(a, b, c, d, e);
final DefaultExecutionTopology topology =
DefaultExecutionTopology.fromExecutionGraph(simpleTestGraph);
final DefaultSchedulingPipelinedRegion firstPipelinedRegion =
topology.getPipelinedRegionOfVertex(new ExecutionVertexID(a.getID(), 0));
final DefaultSchedulingPipelinedRegion secondPipelinedRegion =
topology.getPipelinedRegionOfVertex(new ExecutionVertexID(e.getID(), 0));
final DefaultExecutionVertex vertexB0 =
topology.getVertex(new ExecutionVertexID(b.getID(), 0));
final IntermediateResultPartitionID b0ConsumedResultPartition =
Iterables.getOnlyElement(vertexB0.getConsumedResults()).getId();
final Set<IntermediateResultPartitionID> secondPipelinedRegionConsumedResults =
IterableUtils.toStream(secondPipelinedRegion.getConsumedResults())
.map(DefaultResultPartition::getId)
.collect(Collectors.toSet());
assertThat(firstPipelinedRegion.getConsumedResults().iterator().hasNext(), is(false));
assertThat(secondPipelinedRegionConsumedResults, contains(b0ConsumedResultPartition));
}