in sample/src/main/java/org/apache/apisix/plugin/runner/filter/PostReqWithVarsFilter.java [40:47]
public void filter(HttpRequest request, HttpResponse response, PluginFilterChain chain) {
String configStr = request.getConfig(this);
Gson gson = new Gson();
Map<String, Object> conf = new HashMap<>();
conf = gson.fromJson(configStr, conf.getClass());
request.setPath((String) conf.get("rewrite_path"));
chain.filter(request, response);
}