Why the jar package conflicts

I need to use two jar packages in my project

<dependency>
    <groupId>com.aliyun.openservices</groupId>
    <artifactId>aliyun-log-logback-appender</artifactId>
    <version>0.1.15</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

Among them, aliyun-log-logback-appender depends on

<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-core</artifactId>
    <version>1.2.3</version>
</dependency>
<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.2.3</version>
</dependency>

spring-boot-starter-web依赖

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

spring-boot-starter又依赖

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

spring-boot-starter-logging依赖

<dependency>
   <groupId>ch.qos.logback</groupId>
   <artifactId>logback-classic</artifactId>
</dependency>

At this time, the logback_classic version is

1.1.11

According to the priority of the delivery of dependencies, the version that should be introduced is 1.2.3 but the version actually referenced in my project is 1.1.11

So an error was reported when the project started. Why?