env0_cost_credentials_project_assignment Not Working - "Bad Request: /body must be object"

[paul-hugill]

When trying to assign Cost Credentials to a Project, I get the following error:
Error: could not assign cost credentials to project: 400 Bad Request: /body must be object

My code is:

resource "env0_aws_cost_credentials" "cost" {
  name        = "${var.account_name}-cost"
  arn         = aws_iam_role.env0_cost.arn
  external_id = "$${ssm:env0/${var.org_name}/cost-external-id}"
}
resource "env0_cost_credentials_project_assignment" "cost" {
  credential_id = env0_aws_cost_credentials.cost.id
  project_id    = env0_project.main.id
}

Provider version 1.0.2 in use.
Have tested with both TF version 0.13.7 and 1.0.8 just to rule it out.

I'm probably wrong but looks like the issue might be here:

terraform-provider-env0/client/cost_credentials_project_assignment.go

Line 12 in ef98001

err := client.http.Put("/costs/project/"+projectId+"/credentials", credentialId, &result)

According to the API, it expects the body as a json object:

'{
  "credentialsId": "string"
}'

If I am not mistaken, looks like it is just be being passed in as a string of the ID itself but my GoLang is not that strong so I could be well off.