Adding the fix for retention rule issue for existing bucket

ibm/service/cos/resource_ibm_cos_bucket.go

@@ -357,7 +357,6 @@ func ResourceIBMCOSBucket() *schema.Resource {
 				Optional:    true,
 				MaxItems:    1,
 				Description: "A retention policy is enabled at the IBM Cloud Object Storage bucket level. Minimum, maximum and default retention period are defined by this policy and apply to all objects in the bucket.",
-				ForceNew:    true,
 				Elem: &schema.Resource{
 					Schema: map[string]*schema.Schema{
 						"default": {

ibm/service/cos/resource_ibm_cos_bucket_test.go

@@ -1590,6 +1590,42 @@ func TestAccIBMCosBucket_Retention(t *testing.T) {
 	})
 }
 
+func TestAccIBMCosBucket_Retention_Rule_Existing_bucket(t *testing.T) {
+	cosCrn := acc.CosCRN
+	bucketName := fmt.Sprintf("terraform%d", acctest.RandIntRange(10, 100))
+	bucketRegion := "us-south"
+	bucketClass := "standard"
+	bucketRegionType := "region_location"
+	default_retention := 0
+	maximum_retention := 1
+	minimum_retention := 0
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { acc.TestAccPreCheck(t) },
+		Providers:    acc.TestAccProviders,
+		CheckDestroy: testAccCheckIBMCosBucketDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccCheckIBMCosBucket_retention_basic_bucket(bucketName, cosCrn, bucketRegionType, bucketRegion, bucketClass),
+				Check: resource.ComposeAggregateTestCheckFunc(
+					resource.TestCheckResourceAttr("ibm_cos_bucket.bucket", "bucket_name", bucketName),
+					resource.TestCheckResourceAttr("ibm_cos_bucket.bucket", "storage_class", bucketClass),
+					resource.TestCheckResourceAttr("ibm_cos_bucket.bucket", "region_location", bucketRegion),
+				),
+			},
+			{
+				Config: testAccCheckIBMCosBucket_retention_existing_bucket(bucketName, cosCrn, bucketRegionType, bucketRegion, bucketClass, default_retention, maximum_retention, minimum_retention),
+				Check: resource.ComposeAggregateTestCheckFunc(
+					resource.TestCheckResourceAttr("ibm_cos_bucket.bucket", "bucket_name", bucketName),
+					resource.TestCheckResourceAttr("ibm_cos_bucket.bucket", "storage_class", bucketClass),
+					resource.TestCheckResourceAttr("ibm_cos_bucket.bucket", "region_location", bucketRegion),
+					resource.TestCheckResourceAttr("ibm_cos_bucket.bucket", "retention_rule.#", "1"),
+				),
+			},
+		},
+	})
+}
+
 func TestAccIBMCosBucket_Object_Versioning(t *testing.T) {
 
 	cosServiceName := fmt.Sprintf("cos_instance_%d", acctest.RandIntRange(10, 100))
@@ -3487,6 +3523,42 @@ func testAccCheckIBMCosBucket_retention(cosServiceName string, bucketName string
 	`, cosServiceName, bucketName, region, storageClass, default_retention, maximum_retention, minimum_retention)
 }
 
+func testAccCheckIBMCosBucket_retention_basic_bucket(bucketName string, cosCrn string, regiontype string, region string, storageClass string) string {
+
+	return fmt.Sprintf(`
+	data "ibm_resource_group" "cos_group" {
+		name = "Default"
+	}
+
+	resource "ibm_cos_bucket" "bucket" {
+		bucket_name           = "%s"
+		resource_instance_id  = "%s"
+	    region_location       = "%s"
+		storage_class         = "%s"
+	}
+	`, bucketName, cosCrn, region, storageClass)
+}
+func testAccCheckIBMCosBucket_retention_existing_bucket(bucketName string, cosCrn string, regiontype string, region string, storageClass string, default_retention int, maximum_retention int, minimum_retention int) string {
+
+	return fmt.Sprintf(`
+	data "ibm_resource_group" "cos_group" {
+		name = "Default"
+	}
+
+	resource "ibm_cos_bucket" "bucket" {
+		bucket_name           = "%s"
+		resource_instance_id  = "%s"
+	    region_location       = "%s"
+		storage_class         = "%s"
+		retention_rule {
+			default = %d
+			maximum = %d
+			minimum = %d
+			permanent = false
+		}
+	}
+	`, bucketName, cosCrn, region, storageClass, default_retention, maximum_retention, minimum_retention)
+}
 func testAccCheckIBMCosBucket_object_versioning(cosServiceName string, bucketName string, regiontype string, region string, storageClass string, enable bool) string {
 
 	return fmt.Sprintf(`