Usage of non existing minor_road class of transportation

[frodrigo]

The tunnel-minor layer use a filter on class minor_road. But this class does not exist on OMT. So the layer tunnel-minor render nothing.

The style look like this

1. Applying the same style as trunk...tertiary done this:

{
  "id": "tunnel-minor",
  "type": "line",
  "metadata": {
    "mapbox:group": "1444849354174.1904"
  },
  "source": "openmaptiles",
  "source-layer": "transportation",
  "filter": [
    "all",
    ["==", "brunnel", "tunnel"],
    ["==", "class", "minor"]
  ],
  "layout": {"line-join": "round"},
  "paint": {
    "line-color": "#fff",
    "line-opacity": 1,
    "line-width": {
      "base": 1.2,
      "stops": [
        [13.5, 0],
        [14, 2.5],
        [20, 11.5]
      ]
    }
  }
}

Round casing cannot be removed.