An optional case-insensitive, comma-separated list of object types to retrieve.
The valid values are defined in the CatalogObjectType enum, for example,
ITEM, ITEM_VARIATION, CATEGORY, DISCOUNT, TAX,
MODIFIER, MODIFIER_LIST, IMAGE, etc.
If this is unspecified, the operation returns objects of all the top level types at the version
of the Square API used to make the request. Object types that are nested onto other object types
are not included in the defaults.
At the current API version the default object types are:
ITEM, CATEGORY, TAX, DISCOUNT, MODIFIER_LIST,
PRICING_RULE, PRODUCT_SET, TIME_PERIOD, MEASUREMENT_UNIT,
SUBSCRIPTION_PLAN, ITEM_OPTION, CUSTOM_ATTRIBUTE_DEFINITION, QUICK_AMOUNT_SETTINGS.