为什么传递参数给运算符函数类的构造函数是空的Flink？

import org.apache.flink.api.common.functions.RichMapFunction;
import org.apache.flink.configuration.Configuration;

public class MyMapFunction extends RichMapFunction<Integer, String> {
    private String parameter;

    public void setParameter(String parameter) {
        this.parameter = parameter;
    }

    @Override
    public void open(Configuration parameters) throws Exception {
        // 在open方法中进行参数的初始化
        this.parameter = parameters.getString("parameter", "");
    }

    @Override
    public String map(Integer value) throws Exception {
        // 使用已初始化的参数进行运算
        return value + parameter;
    }
}

import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.operators.DataSource;
import org.apache.flink.api.java.utils.ParameterTool;

public class FlinkExample {
    public static void main(String[] args) throws Exception {
        ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
        DataSource<Integer> dataSource = env.fromElements(1, 2, 3);

        // 设置参数的值
        ParameterTool parameterTool = ParameterTool.fromArgs(args);
        env.getConfig().setGlobalJobParameters(parameterTool);

        // 创建运算符函数类的实例
        MyMapFunction mapFunction = new MyMapFunction();

        // 将参数传递给运算符函数类
        mapFunction.setParameter(parameterTool.get("parameter"));

        // 使用运算符函数类进行转换操作
        dataSource.map(mapFunction).print();
    }
}