HTTP Datasource base url

Hi,
i'm trying to implement an HTTP resolver by providing a datasource endpoint like this:

https://something.execute-api.us-east-1.amazonaws.com/

and then in the datasource i call it by passing:

"resourcePath": "/dev/function",

And it works!

but then i want to include the stage into de baseurl in the datasource, like so:

https://something.execute-api.us-east-1.amazonaws.com/dev/

and call the resolver with

"resourcePath": "/function",

Now it fails with code 403, forbidden:

"headers": { 
    "Content-Length": "23", 
    "Content-Type": "application/json", 
    "Date": "Thu, 04 Jul 2019 20:16:43 GMT", 
    "Via": "1.1 b27a02320ae6ae78c5c25db5c9ccb9dc.cloudfront.net (CloudFront)", 
    "x-amz-apigw-id": "cUO6vHmcIAMF3dw=", 
    "X-Amz-Cf-Id": "SB7I7xyCfuMvHQk3gZdfj0N9mtriRDPZHlGhhWBH0DQnbi-SyAZWbw==", 
    "X-Amz-Cf-Pop": "IAD53", 
    "x-amzn-ErrorType": "ForbiddenException", 
    "x-amzn-RequestId": "a3cdec9c-9e98-11e9-8060-a336db38c26d", 
    "X-Cache": "Error from cloudfront" 
}, 
"statusCode": 403, 
"body": "{\"message\":\"Forbidden\"}"

I activated the logs in cloudwatch but i cant see any usefull information that can help me debug this, for example, i cant find anywhere in the logs the resolved http url.

Question: is this supported?

Thanks,
Andres