@Consumes(MediaType.APPLICATION_FORM_URLENCODED) did not work with RESTEasy JAX-RS 3.0.4.Final but the form variable was empty. @FormParam works.

The following interface change made it work:

@Consumes(MediaType.APPLICATION_FORM_URLENCODED)
public abstract StatusElement lockRunsForTrips(MultivaluedMap<String, String> form);

to

public abstract StatusElement lockRunsForTrips(@FormParam("run_id") List<String> runIdStrings);