NullPointerException when run getCookieNamePrefix

[silloy]

I extend the ProxyServlet

public class QProxyServlet extends ProxyServlet {

    @Override
    public void init() throws ServletException {
        super.init();
    }

    @Override
    protected void initTarget() {
    }

    @Override
    protected HttpResponse doExecute(HttpServletRequest servletRequest, HttpServletResponse servletResponse, HttpRequest proxyRequest) throws IOException {
        return super.doExecute(servletRequest, servletResponse, proxyRequest);
    }

    @Override
    protected String getConfigParam(String key) {
        return null;
    }

    public static String getHostAttrName() {
        return ATTR_TARGET_HOST;
    }

    @Override
    public HttpHost getTargetHost(HttpServletRequest request) {
        return super.getTargetHost(request);
    }

    @Override
    public String getTargetUri(HttpServletRequest request) {
        return request.getServletPath();
    }
}

When I initiate a request, the following exception occurs:

java.lang.NullPointerException: null
        at org.mitre.dsmiley.httpproxy.ProxyServlet.getCookieNamePrefix(ProxyServlet.java:655)
        at org.mitre.dsmiley.httpproxy.ProxyServlet.getProxyCookieName(ProxyServlet.java:611)
        at org.mitre.dsmiley.httpproxy.ProxyServlet.createProxyCookie(ProxyServlet.java:591)
        at org.mitre.dsmiley.httpproxy.ProxyServlet.copyProxyCookie(ProxyServlet.java:578)
        at org.mitre.dsmiley.httpproxy.ProxyServlet.copyResponseHeader(ProxyServlet.java:562)
        at org.mitre.dsmiley.httpproxy.ProxyServlet.copyResponseHeaders(ProxyServlet.java:547)
        at org.mitre.dsmiley.httpproxy.ProxyServlet.service(ProxyServlet.java:377)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)

Following up on this exception, I found that sevletConfig is empty, but my service has been running on the Linux server for a while. Today, a request suddenly caused this exception, and other requests were normal.

[silloy]

The characteristic of an errored request is that the request body and return are relatively large.