A snippet for updating an existing property on a Product Type.

UpdatePropertyValue.cs

public void Update_Property_Value()
{
    var propertyResource = new Mozu.Api.Resources.Commerce.Catalog.Admin.Attributedefinition.Producttypes.ProductTypePropertyResource(_apiContext);
    var attributeResource = new Mozu.Api.Resources.Commerce.Catalog.Admin.Attributedefinition.AttributeResource(_apiContext);
    var productTypeResource = new Mozu.Api.Resources.Commerce.Catalog.Admin.Attributedefinition.ProductTypeResource(_apiContext);
    var attribute = attributeResource.GetAttributeAsync("tenant~color").Result;
    var existingProperty = propertyResource.GetPropertyAsync(17, "tenant~color").Result;
    existingProperty.VocabularyValues.Add(new AttributeVocabularyValueInProductType() 
        {  
            Order = 0,
            Value = "Silver",
            VocabularyValueDetail = new AttributeVocabularyValue()
            {
                Content = new AttributeVocabularyValueLocalizedContent()
                {
                    StringValue = "Silver"
                },
                Value = "Silver",
                ValueSequence = 0
            }
        }
    );

    var updatedProperty = propertyResource.UpdatePropertyAsync(existingProperty, 17, attribute.AttributeFQN).Result;
}