Hi,
Its true there is limited documentation to use this feature but it is straight forward to implement.
Create a node of type granite/ui/components/coral/foundation/authorizable/autocomplete
Create child node of above of type granite/ui/components/coral/foundation/authorizable/selectdatasource
Please check below for query
https://helpx.adobe.com/experience-manager/6-5/sites/developing/using/reference-materials/javadoc/in...
Can you please share where it is used? for dynamic participants it is not used but for participants without selectdatasource
/libs/cq/workflow/components/model/dynamic_participant/cq:dialog/content/items
/libs/cq/workflow/components/model/participant/cq:dialog/content/items/participant/items/columns/items/participant