Use post request to generate api

Dear all,
I’m trying to use the “/api/generate.json” endpoint to post a simple schema and generate data in json format.
But the only response I receive from the API is:

    "error": "A JSON text must at least contain two octets!"

My request is:

curl --location --request POST '' \
--header 'Content-Type: application/json' \
--data-raw '[
      "name" : "blah"
    , "percentBlank": 0
    , "type" : "Color"

Do I miss something?
Thanks for your kind support.