Normalize REST API Policy JSON before unquoting

[strongoose]

Fixes #4397

This is required to unescape non-quote characters, e.g. forward slashes
in CIDR blocks, which the AWS API escapes in its JSON responses.

Acceptance test results to follow.

[strongoose]

Having trouble running acceptance tests locally for some reason, are they covered by the CI?

[bflad]

Thanks for this fix @ouroboros8!! I was able to confirm it by adjusting the existing policy acceptance test to include this condition:

      "Condition": {
          "IpAddress": {
              "aws:SourceIp": "123.123.123.123/32"
          }
      }

Which previously returned:

make testacc TEST=./aws TESTARGS='-run=TestAccAWSAPIGatewayRestApi_policy'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./aws -v -run=TestAccAWSAPIGatewayRestApi_policy -timeout 120m
=== RUN   TestAccAWSAPIGatewayRestApi_policy
--- FAIL: TestAccAWSAPIGatewayRestApi_policy (7.22s)
	testing.go:518: Step 0 error: Error applying: 1 error(s) occurred:

		* aws_api_gateway_rest_api.test: 1 error(s) occurred:

		* aws_api_gateway_rest_api.test: error unescaping policy: invalid syntax
	testing.go:579: Error destroying resource! WARNING: Dangling resources
		may exist. The full state and error is shown below.
		Error: Error refreshing: 1 error(s) occurred:

		* aws_api_gateway_rest_api.test: 1 error(s) occurred:

		* aws_api_gateway_rest_api.test: aws_api_gateway_rest_api.test: error unescaping policy: invalid syntax

		State: <nil>
FAIL
FAIL	github.com/terraform-providers/terraform-provider-aws/aws	7.255s
make: *** [testacc] Error 1

And with the updated code:

make testacc TEST=./aws TESTARGS='-run=TestAccAWSAPIGatewayRestApi_policy'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./aws -v -run=TestAccAWSAPIGatewayRestApi_policy -timeout 120m
=== RUN   TestAccAWSAPIGatewayRestApi_policy
--- PASS: TestAccAWSAPIGatewayRestApi_policy (25.52s)
PASS
ok  	github.com/terraform-providers/terraform-provider-aws/aws	25.555s

[azizbodal]

Awesome, thank you!!!

[bflad]

This has been released in version 1.20.0 of the AWS provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!