object/nightwatch/57 matches the site

public static HumanMadeObject Non_Specific_Relationship()
{
    var nightwatch = new HumanMadeObject()
        .WithContext()
        .WithId("https://linked.art/example/object/nightwatch/57")
        .WithLabel("The Night Watch")
        .WithClassifiedAs(Aat.Painting, Aat.TypeOfWork);

    nightwatch.IdentifiedBy = [new Name("The Night Watch").AsPrimaryName()];

    nightwatch.AttributedBy = [
        new AttributeAssignment()
        {
            IdentifiedBy = [
                new Name("Related Object")
                    .WithClassifiedAs(Aat.DisplayName)
            ],
            Assigned = [
                new HumanMadeObject()
                    .WithId("https://linked.art/example/object/rppob-28-106")
                    .WithLabel("Nachtwacht")
            ],
        }
    ];

    return nightwatch;
}

• Metatype classification The second argument classifies the first, not the object: WithClassifiedAs(Aat.Description, Aat.Statement) says this is a Description, and Description is a kind of Statement. The Plain C# form shows the nesting.
• Role shortcuts AsPrimaryName, AsAccessionNumber and AsSystemAssignedNumber each add a single classification, with the AAT terms Primary Name, Accession Number and System Number.

var humanMadeObject = new HumanMadeObject
{
    Context = ["https://linked.art/ns/v1/linked-art.json"],
    Id = "https://linked.art/example/object/nightwatch/57",
    Label = "The Night Watch",
    ClassifiedAs =
    [
        new Type("http://vocab.getty.edu/aat/300033618", "Painting")
        {
            ClassifiedAs = [Aat.TypeOfWork],
        },
    ],
    IdentifiedBy =
    [
        new Name("The Night Watch")
        {
            ClassifiedAs = [Aat.PrimaryName],
        },
    ],
    AttributedBy =
    [
        new AttributeAssignment
        {
            IdentifiedBy =
            [
                new Name("Related Object")
                {
                    ClassifiedAs = [Aat.DisplayName],
                },
            ],
            Assigned =
            [
                new HumanMadeObject
                {
                    Id = "https://linked.art/example/object/rppob-28-106",
                    Label = "Nachtwacht",
                },
            ],
        },
    ],
};

Generated from the object the example builds: every property that is set, as object initialisers, with the vocabulary constants where a term is in the registry. The fluent helpers are a convenience, not a requirement; this form and the one as written produce the same JSON.