Maven依赖传递排除指定的依赖关系

应用场景：projectA 依赖projectB, projectB 依赖projectC时

projectA中pom.xml
<groupId>com.cn.projectA</groupId>
<artifactId>projectA</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
    <dependency>
        <groupId>com.cn.projectB</groupId>
        <artifactId>projectB</artifactId>
        <version>1.0B</version>
        <!--方案一：使用execusions排除A与C的依赖  -->
        <exclusions>
            <exclusion>
                <groupId>com.cn.projectC</groupId>
                <artifactId>projectC</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
</dependencies>

projectB中的pom.xml
<groupId>com.cn.projectB</groupId>
    <artifactId>projectB</artifactId>
    <version>1.0B</version>
    <dependencies>
        <dependency>
            <groupId>com.cn.projectC</groupId>
            <artifactId>projectC</artifactId>
            <version>1.0C</version>
            <!--依赖传递选项，默认为false为依赖，ture为不依赖传递
            方案二：通过optional设置自动或手动,排除A与C的依赖
                -->
            <optional>false</optional>
        </dependency>
    </dependencies>

    projectC的pom.xml
    <groupId>com.cn.projectC</groupId>
    <artifactId>projectC</artifactId>
    <version>1.0C</version>