课程中关于first的使用，有个地方不明白。为啥结果是(3,Linux)排最前面，我自己跑了好多次都这样。

public class FirstFuncation {

    public static void main(String[] args) throws Exception {
        ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
        List<Tuple2<Integer, String>> info = new ArrayList<Tuple2<Integer, String>>();
        info.add(new Tuple2(1, "Hadoop"));
        info.add(new Tuple2(1, "Spark"));
        info.add(new Tuple2(1, "Flink"));
        info.add(new Tuple2(2, "Java"));
        info.add(new Tuple2(2, "Spring Boot"));
        info.add(new Tuple2(3, "Linux"));
        info.add(new Tuple2(4, "VUE"));

        DataSource<Tuple2<Integer, String>> data = env.fromCollection(info);

        data.groupBy(0).first(2).print();
        System.out.println("~~~~~~~~~~");
    }
}