public int @NotNull [] getPossibleTargetIndices() {
    IntOpenHashSet indices = new IntOpenHashSet();
    for (Trap trap : traps) {
      for (int possibleTarget : trap.getPossibleTargets()) {
        indices.add(possibleTarget);
      }
    }
    for (int possibleTarget : target.getPossibleTargets()) {
      indices.add(possibleTarget);
    }
    return indices.toIntArray();
  }
public int @NotNull [] getPossibleTargetIndices()