code: protected function applyLegendConditions($attributeId, $activeLegendId)
      {
          // No conditions for legend defined.
          if (!isset($this->conditions[$activeLegendId])) {
              return;
          }
  
          if (!isset($this->conditions[$attributeId])) {
              $this->conditions[$attributeId] = new PropertyConditionChain();
          }
  
          $this->conditions[$attributeId]->addCondition($this->conditions[$activeLegendId]);
      }
docs: Apply legend conditions to its attribute.
  
  @param int $attributeId    The attribute setting id.
  @param int $activeLegendId The legend setting id.
  
  @return void