When creating bulk issues using the REST API /rest/api/3/issue/bulk there is a body parameter called Additional Properties. Can this be used to set the issue property (i.e. that set using /rest/api/3/issue/properties/{propertyKey}). If so does anyone have an example?
Instead of the Additional Properties, I think you might be more interested in properties in issueUpdates request parameter. Using Bulk create issue REST API, you can test this basic request body with an entity property being set.