How to use

getSourceId

method

in

mage.abilities.common.DealsDamageToACreatureAttachedTriggeredAbility

@Override
public boolean checkTrigger(GameEvent event, Game game) {
  if (!combatOnly || ((DamagedCreatureEvent) event).isCombatDamage()) {
    Permanent attachment = game.getPermanent(this.getSourceId());
    if (attachment != null
        && attachment.isAttachedTo(event.getSourceId())) {
      if (setTargetPointer) {
        for (Effect effect : this.getEffects()) {
          effect.setTargetPointer(new FixedTarget(event.getTargetId()));
          effect.setValue("damage", event.getAmount());
        }
      }
      return true;
    }
  }
  return false;
}