@Override
  public Val isSet(Val field) {
    if (!(field instanceof StringT)) {
      return noSuchOverload(this, "isSet", field);
    }
    String fieldName = (String) field.value();
    return boolOf(FIELDS.containsKey(fieldName));
  }
Wrapper for a geometry that exposes utility functions to CEL expressions.
planetiler-custommap/src/main/java/com/onthegomap/planetiler/custommap/expression/stdlib/GeometryVal.java