docs: public void addCollision(final String tsuid, final String existing_tsuid) {
      if (tsuid == null || tsuid.isEmpty()) {
        throw new IllegalArgumentException("Empty or null collisions not allowed");
      }
      if (collisions == null) {
        collisions = new HashMap<String, String>();
      }
      if (!collisions.containsKey(tsuid)) {
        collisions.put(tsuid, existing_tsuid);
        changed.put("collisions", true);
      }
    }