Misleading "Invalid certificate" error message when trusted apps IP address not allowed

If JIRA is configured to trust a Confluence server, and receives a RSS request from it, except that the IP address doesn't match, then JIRA sends back a response containing:

X-Seraph-Trusted-App-Status: ERROR
X-Seraph-Trusted-App-Error: Invalid certificate

which Confluence displays:

This message is unhelpful and misleading. What is a "certificate", and why is it invalid? Users don't know or care. The error message ought to be something like "JIRA is not configured to trust the caller's IP address".