The only way I found so far is a workaround.
I query the resource I want and wait till it's there.
run=true;
do {
System.sleep(60000) //wait a minute
jsonObj=vraOperation("GET","/iaas/api/fabric-computes/$filter=name%20eq%20'"+hostShort+"*'",null,false);
if (jsonObj.content.length>0){
if (jsonObj.content[0].type == "Host"){
run=false;
}
}
} while (run);