Using Jena-Fuseki v-5.1.0: I want to set the execution context of a query, but don’t know how to do it. I need to set QuerySendMode to asPostForm.

Following this url guidelines, I’ve created a PREFIX arq (PREFIX arq: http://jena.apache.org/ARQ#), but I’m stuck. I’ve tried to do the following code, but it doesn’t return anything.

SELECT DISTINCT ?x WHERE { ?x arq:httpServiceSendMode 'asPostForm' }

Any ideas?

P.S.: I need to set QuerySendMode to asPostForm, because when doing a sparql federated query to nobelprize, it returns a text instead of the results and I’m thinking that it is because the endpoint returns a form ( see this question