The newest API is still under development. The latest available version is here for creating an engagement.
I am unclear where you are finding these additional parameters. Can you show us an example of where we should expect to see these fields in the UI? I may just be misunderstanding 🙃
I sometimes find the best way to figure out these things is to create it in the UI and the do a get request for it. See what it spits out. For example, I created a task with the additional parameters that you listed above and did a request for that engagement. This is the part you will want to look at that is returned:
"metadata": {
"body": "This is the body of the task.",
"status": "NOT_STARTED",
"forObjectType": "CONTACT",
"subject": "Task title",
"taskType": "CALL",
"reminders": [],
"priority": "HIGH",
"isAllDay": false
}
So with that, you would format your post request body like this as an example:
{
"engagement": {
"active": true,
"ownerId": 1,
"type": "TASK",
"timestamp": 1409172644778
},
"associations": {
"contactIds": [21551]
},
"metadata": {
"body": "This is the body of the task.",
"subject": "Task title",
"status": "NOT_STARTED",
"taskType": "CALL",
"forObjectType": "CONTACT",
"priority": "HIGH"
}
}