Additional "vendor options" property for :ref:`label_obstacles`:

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   * - Property
     - Required?
     - Description
     - Default value
   * - ``x-labelObstacle``
     - No
     - Marks the symbolizer as an obstacle such that labels drawn via a :ref:`text symbolizer <ysld_reference_symbolizers_text>` will not be drawn over top of these features. Options are ``true`` or ``false``. Note that the bounding boxes of features are used when calculating obstacles, so unintended effects may occur when marking a line or polygon symbolizer as an obstacle.
     - ``false``
