If you want your Mechanic Flow trigger to be associated
with a Shopify resource, you may include its numeric ID
below. Only one resource at a time is supported. Leave
this out entirely to use the General Mechanic Flow trigger.
"customer_id": 1234567890,
"product_id": 1234567890,
Keep as many of the following as you like. Any omitted
keys *will* be submitted anyway, using the default value
given below. If you don't want to use Mechanic's default
value, make sure to *keep* the key in place below, setting
"user_url": "https://mechanic.invalid/"