TurfsJoins pointsWithinPolygon => Need more informations

Hello !
First of all, thank you for your work!

I have a service that transforms data into geojson.
I have points and polygons. I want to check if the points are in the polygons. For this, I use "TurfJoins.pointsWithinPolygon()".
But when I pass my two FeatureCollections as parameters, it returns an empty list. Maybe I forgot something?
After several hours of searching, I decide to turn to you. I thank you in advance for your help. I code in Kotlin

class PointWithinPolygonService @Autowired constructor (val tblPolygonRepository: TblPolygonRepository, val pointsService: PointsService) {
     fun withinPolygon(): FeatureCollection {
        val polygons = tblPolygonRepository.findAll()
        val points = pointsService.getPoints()

        val pointsFeatureCollection = FeatureCollection
                .fromFeatures(points
                .filter { it.gpsLongitude != null }
                .map { Feature.fromGeometry(Point.fromLngLat(BigDecimal(it.gpsLongitude!!).setScale(4, RoundingMode.CEILING).toDouble(), BigDecimal(it.gpsLatitude!!).setScale(4, RoundingMode.CEILING).toDouble()))
        })
         
         val polygonsFeatureCollection = FeatureCollection
             .fromFeature(Feature
                 .fromGeometry(Polygon
                     .fromLngLats(polygons
                         .map {it.getListCoordinates()?.map { it -> Point.fromLngLat(it.longitude, it.latitude) } }))
             )
        return TurfJoins.pointsWithinPolygon(pointsFeatureCollection, polygonsFeatureCollection)
    }
}

Comienza por TurfJoins.pointsWithinPolygon y compara la construcción de FeatureCollection proporcionada con las coordenadas de polígono que espera el método; inspecciona el código del servicio Kotlin mostrado, especialmente el filtrado y el orden de las coordenadas. Reproduce el resultado vacío con los mismos puntos y polígonos, y considera que el issue está resuelto cuando se haya identificado la causa y el método devuelva los puntos esperados o se documente la corrección de entrada necesaria.