Making an API Call HTTP Request

Whenever i make an http call, with a GET method, i get an error code 400.
My terminal shows an error of

2021-11-19 16:29:03,825 1996 INFO app odoo.http: <function OdooAPI.get_model_data at 0x7f5ad50729d8>, /api/fleet.vehicle: Function declared as capable of handling request of type ‘http’ but called with a request of type ‘json’

Here are my logics

Thanks in advance.

why wont you use Data in the top toolbar to configure a new REST resource instead?
HTTP request is an advance fucntion when you a custom header but from what I see you would be better off if you configure DATA, use get record