Make binding optional for iam_policy data source

[slevenick]

This will allow a user to specify an IAM policy with no bindings. This can be useful if the user wants to ensure an IAM policy hasn't been manually created

fixes: hashicorp/terraform-provider-google#4500

Release Note for Downstream PRs (will be copied)

`iam`: Allow for empty bindings in `data_source_google_iam_policy` data source

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
I see that this PR has already had some downstream PRs generated. Any open downstreams are already updated to your most recent commit, abeb2a7.

Pull request statuses

No diff detected in terraform-google-conversion.
No diff detected in Ansible.
No diff detected in Inspec.

New Pull Requests

I built this PR into one or more new PRs on other repositories, and when those are closed, this PR will also be merged and closed.
depends: hashicorp/terraform-provider-google-beta#1173
depends: hashicorp/terraform-provider-google#4525

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
I see that this PR has already had some downstream PRs generated. Any open downstreams are already updated to your most recent commit, 8e19c1f.

Pull request statuses

terraform-provider-google-beta already has an open PR.
No diff detected in terraform-google-conversion.
terraform-provider-google already has an open PR.
No diff detected in Ansible.
No diff detected in Inspec.

New Pull Requests

I didn't open any new pull requests because of this PR.

[danawillow]

I'm not totally sure this change is necessary to solve the issue in question (vs just saying bindings = []). Can you confirm?

Also, can you add a comment in the schema about why this is optional, as well as a link in your PR description to the issue it fixes?

[slevenick]

I'm not totally sure this change is necessary to solve the issue in question (vs just saying bindings = []). Can you confirm?

Also, can you add a comment in the schema about why this is optional, as well as a link in your PR description to the issue it fixes?

👍 Will do.

We can't specify bindings = [] in a config, and binding {} also fails,

Error: Unsupported argument

  on file.tf line 6, in data "google_iam_policy" "admin":
   6:     bindings = []

An argument named "bindings" is not expected here.

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
I see that this PR has already had some downstream PRs generated. Any open downstreams are already updated to your most recent commit, ed82274.

Pull request statuses

terraform-provider-google-beta already has an open PR.
No diff detected in terraform-google-conversion.
terraform-provider-google already has an open PR.
No diff detected in Ansible.
No diff detected in Inspec.

New Pull Requests

I didn't open any new pull requests because of this PR.

[emilymye]

LGTM, but out of curiousity, does (singular) binding = [] work? based on error message it could be plural/single issue, but I also don't know if this set-to-list syntax is valid in 0.12

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
I see that this PR has already had some downstream PRs generated. Any open downstreams are already updated to your most recent commit, 69c403d.

Pull request statuses

terraform-provider-google-beta already has an open PR.
No diff detected in terraform-google-conversion.
terraform-provider-google already has an open PR.
No diff detected in Ansible.
No diff detected in Inspec.

New Pull Requests

I didn't open any new pull requests because of this PR.