 an array of objects with key/value fields. For example:
[
  {"key": "google_channel_row", "value": "foo"}
]
This is matched to a section in the search configuration:
"params": [
  {
    "name": "channel",
    "experimentConfig": "google_channel_row"
  }
],
In this case, the resulting URL for the appropriate search engine would have `&channel=foo` added to the URL when doing searches.
If the key is not referenced in the search configuration, then no parameter will be added. If the parameter is in the search configuration, but there is no experiment, or the experiment does not set a value, then the parameter will not be included in the search url.
Only the search team can update the configuration.N