Confluence Page gadget throws "The resource rest/webResources/1.0/resources, cannot be found." error

Summary

After creating an application link between JIRA and Confluence, have JIRA subscribe to Confluence gadget and add the Confluence Page Gadget to a JIRA dashboard. You will see the following error in it.

Steps to Reproduce

1. Install JIRA 6.4.7 with context path (http://localhost:6471/jira)
2. Install Confluence 5.8.4 with context path (http://localhost:5841/conf)
3. Create an AppLink between them
4. Subscribe to Confluence gadget in JIRA
5. Add the Confluence Page Gadget to a JIRA dashboard
6. Select a space and a page

Expected Results

The page shows up fine with no error

Actual Results

You will see the below error while nothing is thrown in the logs:

The resource /conf/rest/webResources/1.0/resources, cannot be found

Clicking on the link will redirect to http://localhost:6471/conf/rest/webResources/1.0/resources which is the wrong port/context path combination

Notes

• Tested with both Trusted Application and OAuth
• Also tested with JIRA 6.3.15 and Confluence 5.8.4
• Does not happen with JIRA 6.4.7 and Confluence 5.7

Workaround

If JIRA and Confluence URLs do not have a context path, the error doesn't appear.