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
protected boolean preserveIndicesUponCompletion() {
        return true;
    }
    public void testBasicGet() throws Exception {
        final Request mvtRequest = new Request(getHttpMethod(), INDEX_POINTS + "/_mvt/location/" + z + "/" + x + "/" + y);
        mvtRequest.setJsonEntity("{\"size\" : 100}");
        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);
    }
    public void testIndexAllGet() throws Exception {
        final Request mvtRequest = new Request(getHttpMethod(), INDEX_ALL + "/_mvt/location/" + z + "/" + x + "/" + y);
        mvtRequest.setJsonEntity("{\"size\" : 100}");
        final VectorTile.Tile tile = execute(mvtRequest);
        assertThat(tile.getLayersCount(), Matchers.equalTo(3));
        
        assertLayer(tile, HITS_LAYER, 4096, 36, 2);
        assertLayer(tile, AGGS_LAYER, 4096, 256 * 256, 2);
        assertLayer(tile, META_LAYER, 4096, 1, 13);
    }
    public void testExtent() throws Exception {
        final Request mvtRequest = new Request(getHttpMethod(), INDEX_POINTS + "/_mvt/location/" + z + "/" + x + "/" + y);
        mvtRequest.setJsonEntity("{\"size\" : 100, \"extent\" : 256}");
        final VectorTile.Tile tile = execute(mvtRequest);
        assertThat(tile.getLayersCount(), Matchers.equalTo(3));
        assertLayer(tile, HITS_LAYER, 256, 33, 2);
        assertLayer(tile, AGGS_LAYER, 256, 1, 2);
        assertLayer(tile, META_LAYER, 256, 1, 13);