Does Confluence Server has an alternative to the "Custom Content" for Cloud?

[Mikkel Djurhuus]

I've developed an addon for confluence cloud where i use custom content to store data.

When trying to migrate the addon to a p2 plugin for server, i can't find any documentation on working with custom content.

Is there a server soloution for creating custom content? (https://developer.atlassian.com/cloud/confluence/modules/custom-content/)