Retrieving a large board with Burndown Chart Gadget does not work

Issue Summary

When using the Sprint Burndown Gadget to retrieve a large board (with more than 100 reports/issues), the same will only display blank content, without the current content of the board in Jira.

Steps to Reproduce

1. In Confluence, make sure to have a new page created
2. In this page, insert the Sprint Burndown Gadget gadget
3. Edit the gadget in order to point to a board with a large number of requests

Expected Results

The gadget should retrieve the chart with the correct content from Jira.

Actual Results

Only blank content is displayed on the gadget:

Workaround

Insert a link to the Jira report on the page, so the users will see the content properly.