Set api annotation on classdesc, not constructor

src/ol/source/XYZ.js

@@ -44,27 +44,27 @@ import {createXYZ, extentFromProjection} from '../tilegrid.js';
  */
 
 
+/**
+ * @classdesc
+ * Layer source for tile data with URLs in a set XYZ format that are
+ * defined in a URL template. By default, this follows the widely-used
+ * Google grid where `x` 0 and `y` 0 are in the top left. Grids like
+ * TMS where `x` 0 and `y` 0 are in the bottom left can be used by
+ * using the `{-y}` placeholder in the URL template, so long as the
+ * source does not have a custom tile grid. In this case,
+ * {@link module:ol/source/TileImage} can be used with a `tileUrlFunction`
+ * such as:
+ *
+ *  tileUrlFunction: function(coordinate) {
+ *    return 'http://mapserver.com/' + coordinate[0] + '/' +
+ *        coordinate[1] + '/' + coordinate[2] + '.png';
+ *    }
+ *
+ * @api
+ */
 class XYZ extends TileImage {
-
   /**
-   * @classdesc
-   * Layer source for tile data with URLs in a set XYZ format that are
-   * defined in a URL template. By default, this follows the widely-used
-   * Google grid where `x` 0 and `y` 0 are in the top left. Grids like
-   * TMS where `x` 0 and `y` 0 are in the bottom left can be used by
-   * using the `{-y}` placeholder in the URL template, so long as the
-   * source does not have a custom tile grid. In this case,
-   * {@link module:ol/source/TileImage} can be used with a `tileUrlFunction`
-   * such as:
-   *
-   *  tileUrlFunction: function(coordinate) {
-   *    return 'http://mapserver.com/' + coordinate[0] + '/' +
-   *        coordinate[1] + '/' + coordinate[2] + '.png';
-   *    }
-   *
-   *
    * @param {module:ol/source/XYZ~Options=} opt_options XYZ options.
-   * @api
    */
   constructor(opt_options) {
     const options = opt_options || {};