Issue #3303759 by alansaviolobo, vdsh: clustering on a external geojson data source

        for (key in myFeatures) {

          if ({}.hasOwnProperty.call(myFeatures, key)) {

            var geojsonLayer = new L.GeoJSON(myFeatures[key], Drupal.leafletBBox.geoJSONOptions);

            // to cluster on external data source, see https://www.drupal.org/project/leaflet_geojson/issues/3303759

            if (typeof L.markerClusterGroup() === 'object') {

              var markerClusterGroup = L.markerClusterGroup();

              markerClusterGroup.addLayer(geojsonLayer);

              layerGroup.addLayer(markerClusterGroup);

            }

            else {

              layerGroup.addLayer(geojsonLayer);

            }

          }

        }

        // TODO: would probably fail with multiple layers, to improve.

        $('.block-map-loading-wrapper').hide();