Hello Everyone, I am trying to explore flink-cep library and trying to run a sample job to start, But its not producing any output. Please let me know if i am doing something wrong.

package org.example;
import org.apache.flink.cep.CEP;
import org.apache.flink.cep.PatternSelectFunction;
import org.apache.flink.cep.pattern.Pattern;
import org.apache.flink.cep.pattern.conditions.SimpleCondition;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;

import java.util.List;
import java.util.Map;

public class FlinkCEPExample {
    public static void main(String[] args) throws Exception {
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        DataStream<Event> events = env.fromElements(
                new Event(1, "start"),
                new Event(2, "middle"),
                new Event(3, "end")
        );

        Pattern<Event, ?> pattern = Pattern.<Event>begin("start")
                .where(SimpleCondition.of(event -> event.getName().equals("start")))
                .followedBy("middle")
                .where(SimpleCondition.of(event -> event.getName().equals("middle")))
                .followedBy("end")
                .where(SimpleCondition.of(event -> event.getName().equals("end")));

        DataStream<String> output = CEP.pattern(events, pattern)
                .select(new PatternSelectFunction<Event, String>() {
                    @Override
                    public String select(Map<String, List<Event>> pattern) throws Exception {
                        StringBuilder result = new StringBuilder();
                        for (Event event : pattern.get("start")) {
                            result.append(event.getId()).append("-");
                        }
                        result.append(pattern.get("middle").get(0).getId()).append("-");
                        result.append(pattern.get("end").get(0).getId());
                        return result.toString();
                    }
                });
        output.print();
        // Execute the job
        env.execute("Flink CEP Pattern Example");
    }
}