shenyu2.5.0报错Expected a com.google.gson.JsonObject but was com.google.gson.JsonPrimitive; at path $

一、环境

shenyu：2.5.0 业务服务接入方式： http shen-admin的数据数据同步方式：websocket

二、异常描述

当shenyu-admin启动或者业务服务注册到admin时，报错

2022-10-12 00:06:10 [main] ERROR org.apache.shenyu.admin.service.manager.impl.DocManagerImpl - getDocInfo error={}
com.google.gson.JsonSyntaxException: Expected a com.google.gson.JsonObject but was com.google.gson.JsonPrimitive; at path $
  at com.google.gson.internal.bind.TypeAdapters$34$1.read(TypeAdapters.java:920)
  at com.google.gson.Gson.fromJson(Gson.java:991)
  at com.google.gson.Gson.fromJson(Gson.java:956)
  at com.google.gson.Gson.fromJson(Gson.java:905)
  at com.google.gson.Gson.fromJson(Gson.java:876)
  at org.apache.shenyu.common.utils.GsonUtils.fromJson(GsonUtils.java:135)
  at org.apache.shenyu.admin.service.manager.impl.DocManagerImpl.getDocInfo(DocManagerImpl.java:101)
  at org.apache.shenyu.admin.service.manager.impl.DocManagerImpl.addDocInfo(DocManagerImpl.java:85)
  at org.apache.shenyu.admin.service.manager.impl.ServiceDocManagerImpl.pullApiDocument(ServiceDocManagerImpl.java:72)
  at java.lang.Iterable.forEach(Iterable.java:75)
  at org.apache.shenyu.admin.service.manager.impl.ServiceDocManagerImpl.pullApiDocument(ServiceDocManagerImpl.java:53)
  at org.apache.shenyu.admin.service.manager.impl.LoadServiceDocEntryImpl.loadApiDocument(LoadServiceDocEntryImpl.java:100)
  at org.apache.shenyu.admin.listener.ApplicationStartListener.onApplicationEvent(ApplicationStartListener.java:49)
  at org.apache.shenyu.admin.listener.ApplicationStartListener.onApplicationEvent(ApplicationStartListener.java:33)
  at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:176)
  at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:169)
  at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:143)
  at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:421)
  at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:378)
  at org.springframework.boot.web.servlet.context.WebServerStartStopLifecycle.start(WebServerStartStopLifecycle.java:46)
  at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178)
  at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54)
  at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356)
  at java.lang.Iterable.forEach(Iterable.java:75)
  at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:155)
  at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:123)
  at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935)
  at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586)
  at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145)
  at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:745)
  at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:420)
  at org.springframework.boot.SpringApplication.run(SpringApplication.java:307)
  at org.springframework.boot.SpringApplication.run(SpringApplication.java:1317)
  at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306)
  at org.apache.shenyu.admin.ShenyuAdminBootstrap.main(ShenyuAdminBootstrap.java:36)

三、问题定位

当服务注册或者admin启动时，会向业务服务请求获取swagger的元数据

@Service
public class ServiceDocManagerImpl implements ServiceDocManager {
    
    private static final String SWAGGER_V2_PATH = "/v2/api-docs";
    
    // 向业务服务拉取swagger的元数据
    public void pullApiDocument(final UpstreamInstance instance) {
        String clusterName = instance.getClusterName();
        if (!canPull(instance)) {
            LOG.info("api document has been pulled and cannot be pulled againl，instance={}", JsonUtils.toJson(instance));
            return;
        }
        String url = getSwaggerRequestUrl(instance);
        try {
            String body = HTTP_UTILS.get(url, Collections.EMPTY_MAP);
            docManager.addDocInfo(
                clusterName,
                body,
                callback -> LOG.info("load api document successful，clusterName={}, iPandPort={}",
                    clusterName, instance.getIp() + ":" + instance.getPort())
            );
            CLUSTER_LASTSTARTUPTIME_MAP.put(clusterName, instance.getStartupTime());
        } catch (Exception e) {
            LOG.error("add api document fail. url={} error={}", url, e);
        }
    }

    // 拼接Swagger的元数据请求地址
    private String getSwaggerRequestUrl(final UpstreamInstance instance) {
        return "http://" + instance.getIp() + ":" + instance.getPort() + SWAGGER_V2_PATH;

    }

}

当业务服务的注册http的配置为

server:
  port: 8080
  servlet:
    context-path: /spvr

shenyu:
  register:
    registerType: nacos #zookeeper #etcd #nacos #consul
    serverLists: ${spring.cloud.nacos.config.server-addr} #localhost:2181 #http://localhost:2379 #localhost:8848
    props:
      username: nacos
      password: nacos
      nacosNameSpace: ${spring.cloud.nacos.discovery.namespace}
  client:
    http:
      props:
        contextPath: /demo
        isFull: true
        appName: ${spring.application.name}

因为服务默认带着context-path故请求到demo服务时，报出404异常信息， 使用gson无法解析，故报错

四、解决

1. 去除server.servlet.context-path