code: function _getChangedSettings(settings) {
          if (settings && typeof(settings) === "object") {
              return _generator.extractDocumentSettings({generatorSettings: settings}, PLUGIN_ID);
          }
          return null;
      }
docs: Extract generator settings from the "current" or "previous" property of a generatorSettings
  change event. If the supplied value is not actually a settings object, returns null.
  
  @private
  @param {object} settings Settings json object.
  @return {object} Settings object from generator or null.