Consider defining a bean of type ‘com.netflix.discovery.AbstractDiscoveryClientOptionalArgs‘ ...

2021-06-02 07:07:08.545  INFO 4044 --- [           main] com.example.client.ClientApplication     : Starting ClientApplication using Java 15 on DESKTOP-JQL00D4 with PID 4044 (C:\Users\xxx\workspace-spring-tool-suite-4-4.8.1.RELEASE\client\target\classes started by xxx in C:\Users\xxx\workspace-spring-tool-suite-4-4.8.1.RELEASE\client)
2021-06-02 07:07:08.555  INFO 4044 --- [           main] com.example.client.ClientApplication     : No active profile set, falling back to default profiles: default
2021-06-02 07:07:10.045  INFO 4044 --- [           main] o.s.cloud.context.scope.GenericScope     : BeanFactory id=20f69ff4-2081-3357-9eb0-d6af76333385
2021-06-02 07:07:10.945  WARN 4044 --- [           main] s.c.a.AnnotationConfigApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration': Unsatisfied dependency expressed through field 'optionalArgs'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.netflix.discovery.AbstractDiscoveryClientOptionalArgs<?>' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
2021-06-02 07:07:10.969  INFO 4044 --- [           main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2021-06-02 07:07:11.013 ERROR 4044 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

Field optionalArgs in org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration required a bean of type 'com.netflix.discovery.AbstractDiscoveryClientOptionalArgs' that could not be found.

The injection point has the following annotations:
	- @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean of type 'com.netflix.discovery.AbstractDiscoveryClientOptionalArgs' in your configuration.

在配置eureka client时，启动应用后，一直报错，错误信息如上。错误信息提示缺少这样一个class: AbstractDiscoveryClientOptionalArgs，并且还有 No active profile set, falling back to default profiles的提示。

查看解决办法：
在创建project时，只是选择了如下eureka依赖：

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

而eureka client 依赖的com.netflix.discovery.AbstractDiscoveryClientOptionalArgs 最终依赖于 spring-web-5.3.4.jar（https://www.hxstrive.com/article/932.htm 给出了详细解释）

于是我在pom.xml的依赖管理中添加了如下依赖，然后在STS中右击 --> maven --> update project，但是应用仍然启动不起来，报相同的错。

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
</dependency>

把整个项目删除，重新新建工程，在新建时选择eureka client 和 spring-web，再启动，一切正常了。

对比了新建的项目，我发现上面的 spring-boot-starter-web依赖需要添加到pom.xml的<project>标签下的<dependencies>中，而不能添加到<dependencyManagement>下的<dependencies>中。那么问题来了，这两处依赖有什么不同呢？