Solution: The Cargo Load Balancer

import java.util.List;
import java.util.Arrays;
public class LoadBalancer {
    public record Container(String id, double weight, double position) {}
    public static double calculateStabilityScore(List<Container> manifest) {
        return manifest.stream()
            // 1. Filter out nulls first to avoid NullPointerException
            .filter(c -> c != null)
            // 2. Filter out empty containers
            .filter(c -> c.weight() != 0)
            // 3. Map to Moment (Weight * Position)
            .map(c -> c.weight() * c.position())
            // 4. Reduce to a single sum
            .reduce(0.0, (total, moment) -> total + moment);
    }
    public static void main(String[] args) {
        List<Container> manifest = Arrays.asList(
            new Container("C-101", 5000.0, 10.0), // Moment: 50,000
            null,                                 // Error
            new Container("C-102", 2000.0, -5.0), // Moment: -10,000
            new Container("C-103", 0.0, 20.0),    // Empty
            new Container("C-104", 4000.0, 5.0)   // Moment: 20,000
        );
        double totalScore = calculateStabilityScore(manifest);
        
        System.out.println("Total Stability Score: " + totalScore);
    }
}