JSON extractor import not respecting 'flatten' option

[rikatz]

While testing the JSON extractor, I did some changes on that and needed to export and import them.

Exporting the extractors where sucessfuly (as represented on the following code):

{
  "extractors": [
    {
      "condition_type": "none",
      "condition_value": "",
      "converters": [],
      "cursor_strategy": "copy",
      "extractor_config": {
        "flatten": false,
        "key_separator": ".",
        "list_separator": ", ",
        "kv_separator": "="
      },
      "extractor_type": "json",
      "order": 0,
      "source_field": "message",
      "target_field": "message",
      "title": "JSONMessage"
    }
  ],
  "version": "1.2.2 (91c7822)"
}

But when importing this, Graylog changes the option of 'flatten' (from extractor config) to true.

[joschi]

Duplicate of graylog-labs/graylog2-web-interface#1702.