Chart Macro breaking due to Attribute "id" was already specified for element

Chart macro will not render due to error

Error rendering macro 'chart' : org.dom4j.DocumentException: Error on line 1 of document : Attribute "id" was already specified for element "h6". Nested exception: Attribute "id" was already specified for element "h6".

Relates to https://jira.atlassian.com/browse/CONFDEV-4813
where duplicate id fields break the XML parser.

Cause

This is caused by an included page in the Chart macro, where the included page contains headings. The headings are assigned an id tag when they are rendered, and the ids are consequently clashing.

Workarounds

1. Remove the headings from the included page
2. Use the Excerpt Include macro instead of Include, as this strips formatting and as such will not throw the error.