You have to go with
<dependencies>
<dependency>
<groupId>com.my</groupId>
<artifactId>commons-deps</artifactId>
<type>pom</type>
</dependency>
</dependencies>
This will transitively add all dependencies declared in com.my:commons-deps
to your current POM.
Using
<dependencyManagement>
<dependencies>
<dependency>
<groupId>...</groupId>
<artifactId>...</artifactId>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
works as a simple ‘include’ of artifacts versions in your dependency management. Thus, it won’t add any dependency in your project.