fix: Change etag to read-only for aws_cloudfront_response_headers_policy

[acwwat]

Description

This PR is to change the etag argument of the aws_cloudfront_response_headers_policy resource to read-only, since users cannot really set it according to the AWS API reference.

Relations

Closes #38244

References

See #38244 (comment) for list of resources referenced during the investigation.

Output from Acceptance Testing

$ make testacc TESTS=TestAccCloudFrontResponseHeadersPolicy PKG=cloudfront
make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go1.22.5 test ./internal/service/cloudfront/... -v -count 1 -parallel 20 -run='TestAccCloudFrontResponseHeadersPolicy'  -timeout 360m
=== RUN   TestAccCloudFrontResponseHeadersPolicyDataSource_basic
=== PAUSE TestAccCloudFrontResponseHeadersPolicyDataSource_basic
=== RUN   TestAccCloudFrontResponseHeadersPolicy_cors
=== PAUSE TestAccCloudFrontResponseHeadersPolicy_cors
=== RUN   TestAccCloudFrontResponseHeadersPolicy_customHeaders
=== PAUSE TestAccCloudFrontResponseHeadersPolicy_customHeaders
=== RUN   TestAccCloudFrontResponseHeadersPolicy_RemoveHeadersConfig
=== PAUSE TestAccCloudFrontResponseHeadersPolicy_RemoveHeadersConfig
=== RUN   TestAccCloudFrontResponseHeadersPolicy_securityHeaders
=== PAUSE TestAccCloudFrontResponseHeadersPolicy_securityHeaders
=== RUN   TestAccCloudFrontResponseHeadersPolicy_serverTimingHeaders
=== PAUSE TestAccCloudFrontResponseHeadersPolicy_serverTimingHeaders
=== RUN   TestAccCloudFrontResponseHeadersPolicy_disappears
=== PAUSE TestAccCloudFrontResponseHeadersPolicy_disappears
=== CONT  TestAccCloudFrontResponseHeadersPolicyDataSource_basic
=== CONT  TestAccCloudFrontResponseHeadersPolicy_securityHeaders
=== CONT  TestAccCloudFrontResponseHeadersPolicy_customHeaders
=== CONT  TestAccCloudFrontResponseHeadersPolicy_RemoveHeadersConfig
=== CONT  TestAccCloudFrontResponseHeadersPolicy_disappears
=== CONT  TestAccCloudFrontResponseHeadersPolicy_cors
=== CONT  TestAccCloudFrontResponseHeadersPolicy_serverTimingHeaders
--- PASS: TestAccCloudFrontResponseHeadersPolicyDataSource_basic (20.54s)
--- PASS: TestAccCloudFrontResponseHeadersPolicy_disappears (21.17s)
--- PASS: TestAccCloudFrontResponseHeadersPolicy_RemoveHeadersConfig (24.26s)
--- PASS: TestAccCloudFrontResponseHeadersPolicy_customHeaders (24.34s)
--- PASS: TestAccCloudFrontResponseHeadersPolicy_securityHeaders (34.47s)
--- PASS: TestAccCloudFrontResponseHeadersPolicy_cors (34.56s)
--- PASS: TestAccCloudFrontResponseHeadersPolicy_serverTimingHeaders (54.73s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/cloudfront 54.959s

$

[github-actions]

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[github-actions]

Thank you for your contribution! 🚀

Please note that typically Go dependency changes are handled in this repository by dependabot or the maintainers. This is to prevent pull request merge conflicts and further delay reviews of contributions. Remove any changes to the go.mod or go.sum files and commit them into this pull request.

Additional details:

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[github-actions]

Thank you for your contribution! 🚀

Please note that typically Go dependency changes are handled in this repository by dependabot or the maintainers. This is to prevent pull request merge conflicts and further delay reviews of contributions. Remove any changes to the go.mod or go.sum files and commit them into this pull request.

Additional details:

• Check open pull requests with the dependencies label to view other dependency updates.
• If this pull request includes an update the AWS Go SDK (or any other dependency) version, only updates submitted via dependabot will be merged. This pull request will need to remove these changes and will need to be rebased after the existing dependency update via dependabot has been merged for this pull request to be reviewed.
• If this pull request is for supporting a new AWS service:
  • Ensure the new AWS service changes are following the Contributing Guide section on new services, in particular that the dependency addition and initial provider support are in a separate pull request from other changes (e.g. new resources). Contributions not following this item will not be reviewed until the changes are split.
  • If this pull request is already a separate pull request from the above item, you can ignore this message.

[jar-b]

This fix makes sense to me given the context from this comment. However, removal of the optional argument technically represents a breaking change. To avoid impacting to existing configurations where etag is explicitly set, we'll need to wait on this for the next major release (v6.0.0).

[jar-b]

LGTM 🎉

% ake testacc PKG=cloudfront TESTS=TestAccCloudFrontResponseHeadersPolicy_
make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go1.24.1 test ./internal/service/cloudfront/... -v -count 1 -parallel 20 -run='TestAccCloudFrontResponseHeadersPolicy_'  -timeout 360m -vet=off
2025/04/02 14:24:31 Initializing Terraform AWS Provider...

--- PASS: TestAccCloudFrontResponseHeadersPolicy_disappears (13.12s)
--- PASS: TestAccCloudFrontResponseHeadersPolicy_customHeaders (14.79s)
--- PASS: TestAccCloudFrontResponseHeadersPolicy_RemoveHeadersConfig (15.13s)
--- PASS: TestAccCloudFrontResponseHeadersPolicy_securityHeaders (22.62s)
--- PASS: TestAccCloudFrontResponseHeadersPolicy_cors (22.76s)
--- PASS: TestAccCloudFrontResponseHeadersPolicy_serverTimingHeaders (36.80s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/cloudfront 43.546s

[jar-b]

Thanks for your contribution, @acwwat! 👍

[github-actions]

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[github-actions]

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