I request such as the following - note the "" off of the sortkey will sort ascending by default, the query parameter sortKeys also supports the "+" in the syntax.
Will return as a 400 error as it is attempting to parse the sortKeys parameters.
Link to query documentation: https://ea.forgerock.com/docs/idm/rest-api-reference/sec-about-crest.html#about-crest-query
Note: I found this on the processinstance endpoint, but the issue likely lies in the shared sort key parsing for all workflow endpoints that permit sorting.
Setup: Start the contractor onboarding workflow sample, and begin a few processes. the example api call should succeed, with the results sorted in asc order.