Links from JIRA in Activity Stream/Gadgets (this includes other Atlassian products like Confluence) always use relative URLs (/foo/bar) instead of absolute URLs (http://www.example.com/foo/bar). When a user in a different application (Confluence) clicks a link in the Activity Stream/Gadgets generated by JIRA it will give them a 404 not found error (since it will try to load the relative URL in the Confluence base URL).

Reproduction steps:

1. Install JIRA and Confluence (tested with JIRA 6.2.2, 6.3.12, 7.11.2 and Confluence 5.5.3, 5.6.5,6.10.2)
2. Setup an Application Link between the two
3. Subscribe to JIRA gadgets in Confluence
   • This allows you to use the JIRA activity stream gadget
4. Create test data in JIRA
5. Create a page in Confluence with the JIRA activity stream
6. Click the JIRA links that are shown in the stream

Expected behavior

Click the link takes you to the item in JIRA

Actual behavior

The standard Confluence Page not found error or a blank page

Screenshot

The following screenshot shows the relative link in the JIRA activity stream, and what happens when you click the link in an Activity Stream in Confluence: