How do I make PluginUpgradeTask work?

I’m trying to perform certain actions after plugin is installed. I’m familiar with ActiveObjectsUpgradeTask, but since this action has nothing to do with database I’m looking for a more elegant solution. I found an article regarding PluginUpgradeTask, but it’s heavily outdated - when I try to use component element in atlassian-plugin.xml, I’m getting following error:

atlassian-plugin.xml contains a definition of component. This is not allowed when Atlassian-Plugin-Key is set.

Linked help document describes that I shouldn’t be using component element and use @Component annotation instead. This of course doesn’t work. I also found some posts about the need to add package export to pom.xml, so I did:

<Export-Package>
    my.product.configuration.upgrade
</Export-Package>

I also added @ExportAsService(PluginUpgradeTask.class) and @Component annotations to my class.

This task doesn’t run, neither on fresh install nor update. How do I make PluginUpgradeTask work OR what should I use instead to perform actions right after my plugin is installed?

Never mind, turns out I’m an idiot and accidentally clicked “make class abstract” when my IDE whined about not implementing all methods from PluginUpgradeTask interface. I didn’t even need Export-Package entry.