Incorrect Coupling

incorrectcoupling.java

public class IncorrectCoupling {
    public static class Points{
        private String productId;
        private Long totalPoints;

        private PointsMappingExternalSystem pointsMappingExternalSystem;
        private PointsMultiplierExternalSystem pointsMultiplierExternalSystem;

        public Double calculateTotalPoints(){
            return pointsMappingExternalSystem.getPointsMappingFromExternalSystem().stream().map(PointsMapping::getPoints).reduce(0d, Double::sum)
                    * pointsMultiplierExternalSystem.getPointsMultiplierFromExternalSystem().getMultiplier();
        }
    }

    public static class PointsMapping {
        private String productId;
        private Double points;

        public PointsMapping(String productId, Double points) {
            this.productId = productId;
            this.points = points;
        }

        public Double getPoints() {
            return points;
        }
    }

    public static class PointsMappingExternalSystem{
        // contain logic to use http client / database client, get data and then map into objects
        public static List<PointsMapping> getPointsMappingFromExternalSystem() {
            // example
            return Collections.emptyList();
        }
    }

    public static class PointsMultiplier {
        private String id;
        private double multiplier;
        private LocalDateTime startDate;
        private LocalDateTime endDate;

        public double getMultiplier() {
            return multiplier;
        }
    }

    public static class PointsMultiplierExternalSystem{
        // contain logic to use http client / database client, get data and then map into objects
        public static PointsMultiplier getPointsMultiplierFromExternalSystem() {
            //example
            return new PointsMultiplier();
        }
    }
}