Currently if you add a field in the fields parameter with a wildcard, no fields will be added to the hits layer. The situation is even worst if the wildcard matches the field name of the geo_point or geo_shape field, in that case a ClassCastException is thrown.
x-pack/plugin/vector-tile/src/javaRestTest/java/org/elasticsearch/xpack/vectortile/VectorTileRestIT.java
assertLayer(tile, AGGS_LAYER, 4096, 1, 2);
            assertLayer(tile, META_LAYER, 4096, 1, 13);
        }
        {
            final Request mvtRequest = new Request(getHttpMethod(), INDEX_POINTS + "/_mvt/location/" + z + "/" + x + "/" + y);
            mvtRequest.setJsonEntity("{\"grid_precision\": 9 }");
            final ResponseException ex = expectThrows(ResponseException.class, () -> execute(mvtRequest));
            assertThat(ex.getResponse().getStatusLine().getStatusCode(), Matchers.equalTo(HttpStatus.SC_BAD_REQUEST));
        }
    }
    public void testGeoTileGrid() throws Exception {
        doGridAggType(randomBoolean() ? "" : ", \"grid_agg\": \"geotile\"");
    }
    public void testGeoHexGrid() throws Exception {
        doGridAggType(", \"grid_agg\": \"geohex\"");
    }
    private void doGridAggType(String gridAgg) throws Exception {
        {
            final Request mvtRequest = new Request(getHttpMethod(), INDEX_POINTS + "/_mvt/location/" + z + "/" + x + "/" + y);
            mvtRequest.setJsonEntity("{\"size\" : 100" + gridAgg + ",\"grid_type\": \"point\" }");
            final VectorTile.Tile tile = execute(mvtRequest);
            assertThat(tile.getLayersCount(), Matchers.equalTo(3));
            assertLayer(tile, HITS_LAYER, 4096, 33, 2);
            assertLayer(tile, AGGS_LAYER, 4096, 1, 2);
            assertLayer(tile, META_LAYER, 4096, 1, 13);
            assertFeatureType(tile, AGGS_LAYER, VectorTile.Tile.GeomType.POINT);
        }
        {
            final Request mvtRequest = new Request(getHttpMethod(), INDEX_POINTS + "/_mvt/location/" + z + "/" + x + "/" + y);
            mvtRequest.setJsonEntity("{\"size\" : 100" + gridAgg + ", \"grid_type\": \"grid\" }");