如果我们发现字符串消息在5秒内连续5次以字符“a”开头，我需要生成cep事件。
为此，我编写了一个类cepchareventpublisher.java，它将把字符串消息（如下发布的消息）发布到kafka主题“charevent”
已发布消息：

b; date- 2019-06-27 09:05:09.605
a; date- 2019-06-27 09:05:10.160
c; date- 2019-06-27 09:05:10.661
b; date- 2019-06-27 09:05:11.162
c; date- 2019-06-27 09:05:11.669
b; date- 2019-06-27 09:05:12.175
b; date- 2019-06-27 09:05:12.675
b; date- 2019-06-27 09:05:13.176
a; date- 2019-06-27 09:05:13.676
c; date- 2019-06-27 09:05:14.176
b; date- 2019-06-27 09:05:14.677
b; date- 2019-06-27 09:05:15.177
b; date- 2019-06-27 09:05:15.678
c; date- 2019-06-27 09:05:16.178
a; date- 2019-06-27 09:05:16.679
c; date- 2019-06-27 09:05:17.179
c; date- 2019-06-27 09:05:17.680
c; date- 2019-06-27 09:05:18.180
c; date- 2019-06-27 09:05:18.681
c; date- 2019-06-27 09:05:19.181
c; date- 2019-06-27 09:05:19.681
a; date- 2019-06-27 09:05:20.182
c; date- 2019-06-27 09:05:20.682
b; date- 2019-06-27 09:05:21.182
c; date- 2019-06-27 09:05:21.682
b; date- 2019-06-27 09:05:22.183
a; date- 2019-06-27 09:05:22.683
b; date- 2019-06-27 09:05:23.184
a; date- 2019-06-27 09:05:23.684
c; date- 2019-06-27 09:05:24.184
b; date- 2019-06-27 09:05:24.685
b; date- 2019-06-27 09:05:25.186
c; date- 2019-06-27 09:05:25.687
b; date- 2019-06-27 09:05:26.187
a; date- 2019-06-27 09:05:26.687
a; date- 2019-06-27 09:05:27.188
a; date- 2019-06-27 09:05:27.688
b; date- 2019-06-27 09:05:28.188
b; date- 2019-06-27 09:05:28.688

现在我有了一个consumer cepchareventconsumer.java，它将读取来自kafka主题charevent的消息，并过滤以字符“a”开头的消息。
然后，我编写了以下模式来生成cep事件/警报，同时我们发现连续5条消息，该消息在5秒内以字符“a”开头。

Pattern<String, String> pattern = Pattern.<String> begin("start")
                .times(5).greedy().where(new SimpleCondition<String>() {
                    private static final long serialVersionUID = -6301755149429716724L;

                    @Override
                    public boolean filter(String value) throws Exception {
                        return value.split(";")[0].equals("a");
                    }
                }).within(Time.seconds(5));

打印以下cepchareventconsumer.java接收的以字符“a”开头的消息。

2> a; date- 2019-06-27 09:05:10.160
1> a; date- 2019-06-27 09:05:13.676
3> a; date- 2019-06-27 09:05:16.679
2> a; date- 2019-06-27 09:05:20.182
3> a; date- 2019-06-27 09:05:22.683
1> a; date- 2019-06-27 09:05:23.684
3> a; date- 2019-06-27 09:05:26.687
1> a; date- 2019-06-27 09:05:27.188
1> a; date- 2019-06-27 09:05:27.688
1> a; date- 2019-06-27 09:05:29.198
2> a; date- 2019-06-27 09:05:30.199

1> a; date- 2019-06-27 09:05:33.703
1> a; date- 2019-06-27 09:05:35.203
3> a; date- 2019-06-27 09:05:36.705
2> a; date- 2019-06-27 09:05:38.207
1> a; date- 2019-06-27 09:05:39.709
2> a; date- 2019-06-27 09:05:40.209
3> a; date- 2019-06-27 09:05:40.728

打印的警报消息：

4> Found: a; date- 2019-06-27 09:05:26.687

在上面的消息“发现：a；日期-2019-06-27 09:05:26.687”是警报消息。
我不明白Flink是怎么在5秒内计算出连续的5条信息的。我觉得有点不对劲。
我附上源代码的git url（flink cep char事件）。谁能按我的要求把它改一下吗。