code: public void setIconOptional( Boolean value) {
      PropertyValue propertyValue = iconOptional(value);
      constantPropertyUsageMap.put(PROPERTY_ICON_OPTIONAL, propertyValue);
      layer.setProperties(propertyValue);
    }
docs: Set the IconOptional property
  <p>
  If true, text will display without their corresponding icons when the icon collides with other symbols and the text does not.
  </p>
  
  @param value property wrapper value around Boolean