code: function (sector, level, row, column, imagePath) {
              if (!imagePath || (imagePath.length < 1)) {
                  throw new ArgumentError(
                      Logger.logMessage(Logger.LEVEL_SEVERE, "ImageTile", "constructor",
                          "The specified image path is null, undefined or zero length."));
              }
  
              TextureTile.call(this, sector, level, row, column); // args are checked in the superclass' constructor
  
              /**
               * This tile's image path.
               * @type {String}
               */
              this.imagePath = imagePath;
  
              /**
               * The tile whose texture to use when this tile's texture is not available.
               * @type {Matrix}
               */
              this.fallbackTile = null;
  
              // Assign imagePath to gpuCacheKey (inherited from TextureTile).
              this.gpuCacheKey = imagePath;
          }
docs: Constructs an image tile.
  @alias ImageTile
  @constructor
  @classdesc Represents an image applied to a portion of a globe's terrain. Applications typically do not
  interact with this class.
  @augments TextureTile
  @param {Sector} sector The sector this tile covers.
  @param {Level} level The level this tile is associated with.
  @param {Number} row This tile's row in the associated level.
  @param {Number} column This tile's column in the associated level.
  @param {String} imagePath The full path to the image.
  @throws {ArgumentError} If the specified sector or level is null or undefined, the row or column arguments
  are less than zero, or the specified image path is null, undefined or empty.