Combining key value pair to an array

Hi all, 

I have a geojson file, where I would like to concatenate the some key value pair to one as array. I have tried ListConcatenator however it simple concatenate without creating array. You can see the below my attempt and desired result. Thanks in advance. 

Output of ListConcatenator

{
            "type" : "Feature",
            "geometry" : {
                "type" : "LineString",
                "coordinates" : [
                    [ 4.3458008766, 50.8345288033 ],
                    [ 4.346331954, 50.8348774905 ],
                    [ 4.3474423885, 50.8357197041 ]
                ]
            },
            "properties" : {
                "osm_id" : "",
                "osm_way_id" : "30010739",
                "_amenity{0}.amenity" : "hospital",
                "_amenity{1}.amenity" : "pharmacy",
                "_amenity{2}.amenity" : "drinking_water",
                "_amenity{3}.amenity" : "pub",
                "_concatenated" : "hospital,waste_basket,pharmacy,drinking_water,pub"
            }
        }

Desired output 

{
 "type": "Feature",
 "geometry": {
   "type": "LineString",
   "coordinates": [
     [
       4.3458008766,
       50.8345288033
     ],
     [
       4.346331954,
       50.8348774905
     ],
     [
       4.3474423885,
       50.8357197041
     ]
   ]
 },
 "properties": {
   "osm_id": "",
   "osm_way_id": "30010739",
   "_amenity{0}.amenity": "hospital",
   "_amenity{1}.amenity": "pharmacy",
   "_amenity{2}.amenity": "drinking_water",
   "_amenity{3}.amenity": "pub",
   "_concatenated": [
     "hospital",
     "waste_basket",
     "pharmacy",
     "drinking_water",
     "pub"
   ]
 }
}