REST API calls through Pentaho Data Integration (Spoon)

Hello Pentaho Experts,

I am attempting to make a REST API call through REST Client in Pentaho. I have a Api key for authentication. I tried it in Postman, and it works perfectly fine, but Pentaho throws 403 status code. Below is the postman screenshot:

My Pentaho transformation contains two steps. I am passing URL through "Generate Rows" step and then adding Key and Value in the Header:

Generate Rows:

Rest Client (General):

Rest Client (Header):

Any idea what I might be missing here? Expected output is JSON.

I can't speak to the use of passing key/value in Header for authentication, but what has worked for me is to use the Authentication tab to input my credentials or passing an Authentication header with a bearer token.

Authentication Tab: I use this method to generate and return a bearer token from the API. The token is then used as the authentication method in subsequent steps. The "body" includes the scope (i.e.: "reports:read") and grant type ("client_credentials"). The "header" contains the value "application/x-www-form-urlencoded".

Authentication Header: Once a token has been returned from the API, this can be provided in an "authorization" header. Prepend "bearer" to the token value and pass this in the header tab.

I would also recommend looking at the Headers being passed in Postman to ensure you are not missing anything else that might be happening in your call.