Add dependency to custom JAR in current project

I’m creating a custom JAR from a custom sourceSet in my project, like so:

task customJar(type: Jar) {
    classifier = 'custom'
    from sourceSets.custom.output

Now, I’d like for the project that is defining this task to depend on this JAR at runtime, so it’s reflected in the generated POM’s dependencies. I’ve tried to add it as a dependency like so:

dependencies {
    runtime files(customJar.outputs.files.getFiles())

Even then, I have to manually add an entry to the POM file for the custom JAR.

Is there a better way to have Gradle do this for me automatically?

Also, how can I control what dependencies are listed in the POM for the custom JAR? I’m currently adding it to the archives configuration so Maven publishes it when I do an install / uploadArchives. Are there any examples of adding a custom configuration so install / uploadArchives works with both the ‘archives’ and a custom configuration?