DiffSuppressFunc on Optional integer field never sets the value

SDK version

github.com/hashicorp/terraform-plugin-sdk/v2 v2.7.1

Relevant provider source code

func resourceExample() *schema.Resource {
	return &schema.Resource{
		Create: resourceExampleCreate,
		Update: resourceExampleCreate,
		Read:   resourceExampleRead,
		Delete: resourceExampleDelete,
		Importer: &schema.ResourceImporter{
			State: schema.ImportStatePassthrough,
		},

		Schema: map[string]*schema.Schema{
			"requested_validity": {
				Type:         schema.TypeInt,
				Optional:     true,
				ValidateFunc: validation.IntInSlice([]int{7, 30, 90, 365, 730, 1095, 5475}),
				DiffSuppressFunc: func(k, old, new string, d *schema.ResourceData) bool {
					return true
				},
			},
		},
	}
}

Terraform Configuration Files

resource "example" "example" {
  requested_validity = 7
}

Debug Output

https://gist.githubusercontent.com/jacobbednarz/f15e55aa25902b275ae3f5bc2c68ad5c/raw/3e9d8f7931fc453de325e0d517e15131cb2a67a4/gistfile1.txt

Expected Behavior

The requested_validity should be passed to the CRUD method as 7

Actual Behavior

The requested_validity value is passed as 0.

Steps to Reproduce

If you have a Cloudflare account you can run the acceptance tests with (email/chat me on Terraform Slack and I can give you one off credentials)

• git clone https://github.com/cloudflare/terraform-provider-cloudflare.git
• CLOUDFLARE_API_USER_SERVICE_KEY="xxx" CLOUDFLARE_API_KEY="xxx" CLOUDFLARE_EMAIL="xxxx" CLOUDFLARE_DOMAIN="<your_domain_here>" CLOUDFLARE_ZONE_ID="<your_zone_id_here>" TESTARGS='-run "^TestAccCloudflareOriginCACertificate_Basic" -count 1 -parallel 1' make testacc
• See the test fail
• Remove DiffSuppressFunc from the resource
• Re-run test
• Test will pass

No Cloudflare account

• Create a new resource as documented above
• Attempt to apply the resource
• See the CRUD method is getting a zero value (not user defined)
• Remove DiffSuppressFunc attribute
• Attempt to apply the resource
• CRUD method gets correct value and works as expected

References

n/a

Start with the provided resource schema and trace how the SDK handles DiffSuppressFunc for an optional TypeInt field. Reproduce the issue using the minimal Terraform configuration or the documented acceptance-test command, comparing behavior with and without DiffSuppressFunc. Done means requested_validity reaches the CRUD method as 7 while diff suppression remains supported.