As a plugin developer you can use this plugin as dependency of your plugin by adding a dependency tag to your POM.
To add the latest version of this plugin as a maven dependency, use the following:
<dependency>
    <groupId>io.jenkins.plugins</groupId>
    <artifactId>dagshub-branch-source</artifactId>
    <version>19.v23b9b9c2c08f</version>
</dependency>