Using Realm in a Cordova plugin for Android

I am experimenting with using Realm in place of SQLite in my hybrid Android/Cordova app which uses one custom - i.e. written by me - plugin. From the Realm documentation I have figured out that this has to be a two step process

• Instructing Gradle to use the Realm plugin which I am doing via my plugin.xml file as io.realm:realm-gradle-plugin:6.0.2
• "Applying the plugin" which according to the documentation involves issuing a apply plugin: 'realm-android' from the application levelbuild.gradle`file.

It is not clear to me how I do the latter. I tried putting the "apply plugin" statement in a build-extras.gradle file only to have Gradle complain

plugin with id 'realm-android' not found. Clearly, I am doing something wrong here. I'd be grateful to anyone who might be able to put me on the right path.

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