A less hacky solution is to inject a Provider as a field in your class:
@Inject
private Provider<ContainerRequest> containerRequestProvider;
From here, you can access the query params like this:
final ContainerRequest containerRequest = containerRequestProvider.get();
final UriInfo uriInfo = containerRequest.getUriInfo();
final MultivaluedMap<String, String> queryParameters = uriInfo.getQueryParameters();
final List<String> queryParameter = queryParameters.get("q");
...