springcloud 启动错误

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'org.springframework.cloud.netflix.eureka.server.EurekaServerInitializerConfiguration': Unsatisfied dependency expressed through field 'eurekaServerBootstrap'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'eurekaServerBootstrap' defined in class path resource [org/springframework/cloud/netflix/eureka/server/EurekaServerAutoConfiguration.class]: Unsatisfied dependency expressed through method 'eurekaServerBootstrap' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'peerAwareInstanceRegistry' defined in class path resource [org/springframework/cloud/netflix/eureka/server/EurekaServerAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.netflix.eureka.registry.PeerAwareInstanceRegistry]: Factory method 'peerAwareInstanceRegistry' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scopedTarget.eurekaClient' defined in class path resource [org/springframework/cloud/netflix/eureka/EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.netflix.discovery.EurekaClient]: Factory method 'eurekaClient' threw exception; nested exception is java.lang.RuntimeException: Failed to initialize DiscoveryClient!

      <!-- eureka-server -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka-server</artifactId>
        </dependency>
        <!-- Eureka -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-netflix-eureka-server</artifactId>
            <!--<version>2.2.0.BUILD-SNAPSHOT</version>-->
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>

第一、没有添加 hystrix，这是因为新版本的Spring Cloud对熔断器Hystrix有要求，Eureka中必须添加对Hystrix的依赖才可以正常启动。

第二、给 eureka-sever 添加了多余的版本号。

如果接收到：java.lang.ClassNotFoundException：org.apache.http.config.RegistryBuilder 这个错误

 还是不行的话可以加上

    <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpcore</artifactId>
            <version>4.3.3</version>
        </dependency>