_clearSlot(slotName, slotData) {
      const propertyName = slotData.propertyName || slotName;
      const children = this._state[propertyName];
      children.forEach(child => {
        if (instanceOfUI5Element(child)) {
          const childChangeListener = this._getChildChangeListener(slotName);
          if (childChangeListener) {
            child.detachInvalidate.call(child, childChangeListener);
          }
        }
        if (child instanceof HTMLSlotElement) {
          this._detachSlotChange(child, slotName);
        }
      });
      this._state[propertyName] = [];
    }
Removes all children from the slot and detaches listeners, if any
@private