Make enableExactlyOnceDelivery mutable by removing ForceNew (#6486) (#4645)

Signed-off-by: Modular Magician <[email protected]>

Signed-off-by: Modular Magician <[email protected]>

Author: modular-magician

.changelog/6486.txt

@@ -0,0 +1,3 @@
+```release-note:enhancement
+pubsub: made enableExactlyOnceDelivery mutable so that it updates subscription in-place and avoids recreation of the subscription.
+```

google-beta/resource_pubsub_subscription.go

@@ -177,7 +177,6 @@ If this parameter is 0, a default value of 5 is used.`,
 			"enable_exactly_once_delivery": {
 				Type:     schema.TypeBool,
 				Optional: true,
-				ForceNew: true,
 				Description: `If 'true', Pub/Sub provides the following guarantees for the delivery
 of a message with a given value of messageId on this Subscriptions':
 
@@ -702,6 +701,12 @@ func resourcePubsubSubscriptionUpdate(d *schema.ResourceData, meta interface{})
 	} else if v, ok := d.GetOkExists("retry_policy"); !isEmptyValue(reflect.ValueOf(v)) && (ok || !reflect.DeepEqual(v, retryPolicyProp)) {
 		obj["retryPolicy"] = retryPolicyProp
 	}
+	enableExactlyOnceDeliveryProp, err := expandPubsubSubscriptionEnableExactlyOnceDelivery(d.Get("enable_exactly_once_delivery"), d, config)
+	if err != nil {
+		return err
+	} else if v, ok := d.GetOkExists("enable_exactly_once_delivery"); !isEmptyValue(reflect.ValueOf(v)) && (ok || !reflect.DeepEqual(v, enableExactlyOnceDeliveryProp)) {
+		obj["enableExactlyOnceDelivery"] = enableExactlyOnceDeliveryProp
+	}
 
 	obj, err = resourcePubsubSubscriptionUpdateEncoder(d, meta, obj)
 	if err != nil {
@@ -751,6 +756,10 @@ func resourcePubsubSubscriptionUpdate(d *schema.ResourceData, meta interface{})
 	if d.HasChange("retry_policy") {
 		updateMask = append(updateMask, "retryPolicy")
 	}
+
+	if d.HasChange("enable_exactly_once_delivery") {
+		updateMask = append(updateMask, "enableExactlyOnceDelivery")
+	}
 	// updateMask is a URL parameter but not present in the schema, so replaceVars
 	// won't set it
 	url, err = addQueryParams(url, map[string]string{"updateMask": strings.Join(updateMask, ",")})