Remote Publishing 3.0.0 is feature update release.
Publishing API Update
This release of the remote publishing plugin implements a new publishing mechanism using the Confluence REST API. Publishing was previously carried out using the deprecated xml-rpc API. This brings remote publishing up to date with the latest supported updates from Atlassian.
There is no configuration changes required with this update. However if you have specific firewall rules in place that only allow the source Confluence server to access the XML-RPC endpoints on the remote Confluence instance these will need to be updated to allow access to the complete Confluence REST API.
For more information please see the release notes.