set event id on google calendar java -

i tried set eventid on google calendar v3 api in java, gave me 400 error "message": "invalid resource id value.". there way set event id of google calendar ourselves?

thanks

i dont know why cant set id manually, that, because wanted know id retrieve later. , dont have problem. doing wrong.

event event = new event(); event.setid("cita1"); client.events().insert("primary", event).execute(); 

no errors