Java Generic Record

public record Pair<T, U>(T first, U second) {}

Pair<String, Integer> pair = new Pair<>("Count", 42);
String f = pair.first();   // Return type is strictly String
Integer s = pair.second(); // Return type is strictly Integer

public record NumericBounds<T extends Number>(T lower, T upper) {}

public record ValidatedWrapper<T>(T payload) {
    // Compact constructor
    public ValidatedWrapper {
        if (payload == null) {
            throw new NullPointerException("Payload of type T cannot be null");
        }
    }
}

public record ComparableNode<T extends Comparable<T>>(T data) 
       implements Comparable<ComparableNode<T>> {
    
    @Override
    public int compareTo(ComparableNode<T> other) {
        return this.data.compareTo(other.data());
    }
}

public record Container<T>(T item) {
    
    // ILLEGAL: Cannot make a static reference to the non-static type T
    // public static T getDefault() { ... }

    // LEGAL: The static method declares its own independent type parameter <U>
    public static <U> Container<U> empty(U defaultItem) {
        return new Container<>(defaultItem);
    }
}