Misleading error when trying to perform a Confluence site import using a server space backup

Issue Summary

If a customer tries to run a Confluence site import using a Confluence server space backup, they receive a misleading error message:

This file was exported from Confluence Server. We can only import files exported from Confluence Cloud in the site importer. To migrate a site from Confluence Server to Confluence Cloud, use the Confluence Cloud Migration Assistant. If you need additional help, please raise a support request.

Instead, it should tell them to run a Space import instead of the site import.

Steps to Reproduce

1. Generate a space backup from Confluence server/DC
2. Try to perform a site import in Cloud using this backup

Expected Results

Error message saying to use the space import, since it is a space backup

Actual Results

The following error message is thrown:

Workaround

Check the file exportDescriptor.properties in the zip file, if you find the entry exportType=space, use the space import instead of site import.