@Override
    default TagValueProducer tagValueProducer() {
      var parent = parent();
      return parent == null ? TagValueProducer.EMPTY : parent.tagValueProducer();
    }
Makes nested contexts adhere to {@link WithTags} and {@link WithGeometryType} by recursively fetching source
feature from the root context.
planetiler-custommap/src/main/java/com/onthegomap/planetiler/custommap/Contexts.java