错误HTTP500- javax.servlet.ServletException: BeanUtils.populate: NullPointerException

import org.apache.commons.beanutils.BeanUtils;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Map;

public class MyServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        try {
            // 初始化 JavaBean 对象
            MyBean myBean = new MyBean();

            // 获取请求参数
            Map<String, String[]> parameterMap = request.getParameterMap();

            // 检查请求参数是否为空
            for (String key : parameterMap.keySet()) {
                if (parameterMap.get(key) == null || parameterMap.get(key).length == 0) {
                    throw new IllegalArgumentException("Parameter " + key + " is missing");
                }
            }

            // 将请求参数映射到 JavaBean 对象
            BeanUtils.populate(myBean, parameterMap);

            // 处理业务逻辑
            // ...

        } catch (Exception e) {
            // 处理异常
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            response.getWriter().write("Internal Server Error: " + e.getMessage());
        }
    }
}

class MyBean {
    private String name;
    private int age;

    // Getters and Setters
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}