cloud dubbo 与zipkin集成的问题

### Environment

* Dubbo version: 2.7.6
* Operating System version: mac
* Java version: 1.8
* spring cloud alibaba version 2.2.1
* springboot version 2.2.8
* spring cloud version Hoxton.SR5

### Steps to reproduce this issue

1. spring-cloud-starter-dubbo与 spring-cloud-starter-zipkin +rabbit 集成不能启动， zipkin2.reporter.sender 没有实例
```
Description:

Parameter 2 of method reporter in org.springframework.cloud.sleuth.zipkin2.ZipkinAutoConfiguration required a bean of type 'zipkin2.reporter.Sender' that could not be found.

The following candidates were found but could not be injected:
- Bean method 'rabbitSender' in 'ZipkinRabbitSenderConfiguration' not loaded because @ConditionalOnBean (types: org.springframework.amqp.rabbit.connection.CachingConnectionFactory; SearchStrategy: all) did not find any beans of type org.springframework.amqp.rabbit.connection.CachingConnectionFactory
- Bean method 'restTemplateSender' in 'ZipkinRestTemplateSenderConfiguration' not loaded because ZipkinSender org.springframework.cloud.sleuth.zipkin2.sender.ZipkinRestTemplateSenderConfiguration rabbit sender type

Action:

Consider revisiting the entries above or defining a bean of type 'zipkin2.reporter.Sender' in your configuration.

11:57:22.561 ERROR [main] [,] c.l.DubboProviderApplication.main-32 : Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:156)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:545)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315)
at com.luyanfeng.DubboProviderApplication.main(DubboProviderApplication.java:30)
Caused by: org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:125)
at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.(TomcatWebServer.java:87)
at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:437)
at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:191)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:180)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:153)
... 6 common frames omitted
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'tracingFilter' defined in class path resource [org/springframework/cloud/sleuth/instrument/web/TraceWebServletAutoConfiguration.class]: Unsatisfied dependency expressed through method 'tracingFilter' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'httpTracing' defined in class path resource [org/springframework/cloud/sleuth/instrument/web/TraceHttpAutoConfiguration.class]: Unsatisfied dependency expressed through method 'httpTracing' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'tracing' defined in class path resource [org/springframework/cloud/sleuth/autoconfig/TraceAutoConfiguration.class]: Unsatisfied dependency expressed through method 'tracing' parameter 6; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'zipkinReporter' defined in class path resource [org/springframework/cloud/sleuth/zipkin2/ZipkinAutoConfiguration.class]: Unsatisfied dependency expressed through method 'reporter' parameter 2; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'zipkin2.reporter.Sender' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Qualifier(value=zipkinSender)}
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:797)
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:538)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:207)
at org.springframework.boot.web.servlet.ServletContextInitializerBeans.getOrderedBeansOfType(ServletContextInitializerBeans.java:211)
at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAsRegistrationBean(ServletContextInitializerBeans.java:174)
at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAsRegistrationBean(ServletContextInitializerBeans.java:169)
at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAdaptableBeans(ServletContextInitializerBeans.java:154)
at org.springframework.boot.web.servlet.ServletContextInitializerBeans.(ServletContextInitializerBeans.java:86)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.getServletContextInitializerBeans(ServletWebServerApplicationContext.java:253)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.selfInitialize(ServletWebServerApplicationContext.java:227)
at org.springframework.boot.web.embedded.tomcat.TomcatStarter.onStartup(TomcatStarter.java:53)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5128)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:841)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:930)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.startup.Tomcat.start(Tomcat.java:468)
at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:106)
... 11 common frames omitted
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'httpTracing' defined in class path resource [org/springframework/cloud/sleuth/instrument/web/TraceHttpAutoConfiguration.class]: Unsatisfied dependency expressed through method 'httpTracing' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'tracing' defined in class path resource [org/springframework/cloud/sleuth/autoconfig/TraceAutoConfiguration.class]: Unsatisfied dependency expressed through method 'tracing' parameter 6; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'zipkinReporter' defined in class path resource [org/springframework/cloud/sleuth/zipkin2/ZipkinAutoConfiguration.class]: Unsatisfied dependency expressed through method 'reporter' parameter 2; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'zipkin2.reporter.Sender' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Qualifier(value=zipkinSender)}
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:797)
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:538)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1304)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1224)
at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:884)
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:788)
... 52 common frames omitted
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'tracing' defined in class path resource [org/springframework/cloud/sleuth/autoconfig/TraceAutoConfiguration.class]: Unsatisfied dependency expressed through method 'tracing' parameter 6; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'zipkinReporter' defined in class path resource [org/springframework/cloud/sleuth/zipkin2/ZipkinAutoConfiguration.class]: Unsatisfied dependency expressed through method 'reporter' parameter 2; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'zipkin2.reporter.Sender' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Qualifier(value=zipkinSender)}
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:797)
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:538)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1304)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1224)
at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:884)
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:788)
... 66 common frames omitted
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'zipkinReporter' defined in class path resource [org/springframework/cloud/sleuth/zipkin2/ZipkinAutoConfiguration.class]: Unsatisfied dependency expressed through method 'reporter' parameter 2; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'zipkin2.reporter.Sender' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Qualifier(value=zipkinSender)}
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:797)
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:538)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.addCandidateEntry(DefaultListableBeanFactory.java:1522)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1486)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveMultipleBeans(DefaultListableBeanFactory.java:1375)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1262)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1224)
at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:884)
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:788)
... 80 common frames omitted
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'zipkin2.reporter.Sender' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Qualifier(value=zipkinSender)}
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1714)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1270)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1224)
at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:884)
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:788)
... 97 common frames omitted
```
2. spring-cloud-starter-dubbo 与 brave-instrumentation-dubbo-rpc 集成，导致dubbo的包名引用出问题，然后就是consumer找不到provider. (改用 brave-instrumentation-dubbo好了)

3. spring-cloud-starter-dubbo 与 spring-boot-devtools 集成不能启动：
```
11:54:44.638 ERROR [restartedMain] [,] c.l.DubboProviderApplication.main-32 : Error creating bean with name 'feignTargeter' defined in class path resource [org/springframework/cloud/openfeign/FeignAutoConfiguration$HystrixFeignTargeterConfiguration.class]: Initialization of bean failed; nested exception is java.lang.IllegalAccessError: class org.springframework.cloud.openfeign.$Proxy182 cannot access its superinterface org.springframework.cloud.openfeign.Targeter
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'feignTargeter' defined in class path resource [org/springframework/cloud/openfeign/FeignAutoConfiguration$HystrixFeignTargeterConfiguration.class]: Initialization of bean failed; nested exception is java.lang.IllegalAccessError: class org.springframework.cloud.openfeign.$Proxy182 cannot access its superinterface org.springframework.cloud.openfeign.Targeter
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:603)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:893)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:879)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:551)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315)
at com.luyanfeng.DubboProviderApplication.main(DubboProviderApplication.java:30)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49)
Caused by: java.lang.IllegalAccessError: class org.springframework.cloud.openfeign.$Proxy182 cannot access its superinterface org.springframework.cloud.openfeign.Targeter
at java.lang.reflect.Proxy.defineClass0(Native Method)
at java.lang.reflect.Proxy.access$300(Proxy.java:228)
at java.lang.reflect.Proxy$ProxyClassFactory.apply(Proxy.java:642)
at java.lang.reflect.Proxy$ProxyClassFactory.apply(Proxy.java:557)
at java.lang.reflect.WeakCache$Factory.get(WeakCache.java:230)
at java.lang.reflect.WeakCache.get(WeakCache.java:127)
at java.lang.reflect.Proxy.getProxyClass0(Proxy.java:419)
at java.lang.reflect.Proxy.newProxyInstance(Proxy.java:719)
at com.alibaba.cloud.dubbo.openfeign.TargeterBeanPostProcessor.postProcessAfterInitialization(TargeterBeanPostProcessor.java:75)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:431)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:595)
... 18 common frames omitted
```

Start by reproducing the integration with Dubbo 2.7.6, Spring Cloud Alibaba, Spring Boot, Spring Cloud Sleuth Zipkin, and RabbitMQ. Inspect ZipkinAutoConfiguration, ZipkinRabbitSenderConfiguration, and ZipkinRestTemplateSenderConfiguration around the missing zipkin2.reporter.Sender. Done means the application starts with the requested tracing integration and provides the required Sender bean.

Written by the indexing model from the issue text.