请教一下 flink stream API 代码里面怎么获取window 的起始时间 和结束时间？

TimeWindow有getStart()和getEnd()方法，参见示例代码：

StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
env.setParallelism(PARALLELISM);
env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);
env.enableCheckpointing(100);
env.setRestartStrategy(RestartStrategies.fixedDelayRestart(3, 0));
env.getConfig().disableSysoutLogging();

env.addSource(new FailingSource(numKeys,
                numElementsPerKey,
                numElementsPerKey / 3))
        .rebalance()
        .timeWindowAll(Time.of(windowSize, MILLISECONDS))
        .apply(new RichAllWindowFunction<Tuple2<Long, IntType>, Tuple4<Long, Long, Long, IntType>, TimeWindow>() {

            private boolean open = false;

            @Override
            public void open(Configuration parameters) {
                assertEquals(1, getRuntimeContext().getNumberOfParallelSubtasks());
                open = true;
            }

            @Override
            public void apply(
                    TimeWindow window,
                    Iterable<Tuple2<Long, IntType>> values,
                    Collector<Tuple4<Long, Long, Long, IntType>> out) {

                // validate that the function has been opened properly
                assertTrue(open);

                int sum = 0;
                long key = -1;

                for (Tuple2<Long, IntType> value : values) {
                    sum += value.f1.value;
                    key = value.f0;
                }
                out.collect(new Tuple4<>(key, window.getStart(), window.getEnd(), new IntType(sum)));
            }
        })
        .addSink(new ValidatingSink(numKeys, numElementsPerKey / windowSize)).setParallelism(1);

env.execute("Tumbling Window Test");

TimeWindow有getStart()和getEnd()方法。