@Override
    public Feature putAttrs(Map<String, Object> attrs) {
      for (Object value : attrs.values()) {
        if (value instanceof ZoomFunction || value instanceof Struct) {
          mustUnwrapValues = true;
          break;
        }
      }
      this.attrs.putAll(attrs);
      return this;
    }
Returns the attribute to put on all output vector tile features at a zoom level.
planetiler-core/src/main/java/com/onthegomap/planetiler/FeatureCollector.java