Read Downtimes with REST-API objects/query/Downtime

I try to read the Downtimes in our icinga2 system with this simple example from an other site:

curl -k -s -u test:*************** ‘https://localhost:5665/v1/objects/downtimes?pretty=1’ -X POST -H ‘Accept: application/json’ -H ‘X-HTTP-Method-Override: GET’ -d ‘{“attrs” : [“end_
time”]}’

and get a

"error": 400,
"status": "Invalid type specified."

maybe the api-call has changed or anything like that?

My second question will be, how ca I filter the output for the author?

thx

Version: 2.11.4