@Override
      public void preprocessOsmWay(OsmElement.Way way) {
        Long featureId = nodes1.get(way.nodes().get(0));
        if (featureId != null) {
          nodes2.add(featureId);
        }
      }
In-memory tests with fake data and profiles to ensure all features work end-to-end.
planetiler-core/src/test/java/com/onthegomap/planetiler/PlanetilerTests.java