如何使jetty在调用servlet前缓冲所有请求体

<Configure class="org.eclipse.jetty.servlet.ServletContextHandler">
    <Set name="contextPath">/</Set>
    <Set name="resourceBase">./webapp</Set>
    <Call name="addFilter">
        <Arg>org.eclipse.jetty.servlets.DoSFilter</Arg>
        <Arg>
            <New class="java.util.EnumSet">
                <Arg type="java.lang.Class">javax.servlet.DispatcherType</Arg>
                <Arg type="java.lang.Enum">REQUEST</Arg>
            </New>
        </Arg>
        <Call name="setInitParameter">
            <Arg>maxRequestsPerSec</Arg>
            <Arg>10</Arg>
        </Call>
    </Call>
</Configure>

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class CustomServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 从请求中获取缓冲的请求体
        String requestBody = req.getReader().lines().collect(Collectors.joining(System.lineSeparator()));
        
        // 处理请求体
        // ...
    }
}

<Configure class="org.eclipse.jetty.servlet.ServletContextHandler">
    <Set name="contextPath">/</Set>
    <Set name="resourceBase">./webapp</Set>
    <Call name="addServlet">
        <Arg>com.example.CustomServlet</Arg>
        <Arg>/custom</Arg>
    </Call>
</Configure>