Trying to create (or update) a data bag item via Chef REST API (using a non-ruby client), a key `action` gets removed

gistfile1.js

// Trying to create a data bag item foo bar with the following json via REST API:
{
  "id": "bar",
  "key": "value",
  "action": "remove"
}

// The POST succeeds, but then the content of the data bag item is:
{
  "id": "bar",
  "key": "value"
}


// This is instead the body of the POST sent by knife data bag from file foo
{
  "name": "data_bag_item_foo_bar",
  "json_class": "Chef::DataBagItem",
  "chef_type": "data_bag_item",
  "data_bag": "foo",
  "raw_data": {
    "id": "bar",
    "key": "value",
    "action": "remove"
  }
}

Sniffing local traffic on the server, I captured this piece of internal communication:

{
  "action": "add",
  "payload": {
    "database": "chef_6b9041972ab04993b137b79597c1e976",
    "id": "f85b20a9-e4ef-4a46-8fb9-14e5bea89c92",
    "type": "data_bag_item",
    "item": {
      "id": "bar",
      "chef_type": "data_bag_item",
      "data_bag": "foo",
      "key": "value"
    },
    "enqueued_at": 1360332842
  }
}