Make RegionBackendService health checks optional

.changelog/4053.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+compute: Fixed an issue where `google_compute_region_backend_service` required `healthChecks` for a serverless network endpoint group.
+```

google/resource_compute_backend_service.go

@@ -458,7 +458,8 @@ requests.`,
 for health checking this BackendService. Currently at most one health
 check can be specified.
 
-A health check must be specified unless the backend service uses an internet NEG as a backend.
+A health check must be specified unless the backend service uses an internet
+or serverless NEG as a backend.
 
 For internal load balancing, a URL to a HealthCheck resource must be specified instead.`,
 				MinItems: 1,

google/resource_compute_region_backend_service.go

@@ -136,19 +136,6 @@ func resourceComputeRegionBackendService() *schema.Resource {
 		CustomizeDiff: customDiffRegionBackendService,
 
 		Schema: map[string]*schema.Schema{
-			"health_checks": {
-				Type:     schema.TypeSet,
-				Required: true,
-				Description: `The set of URLs to HealthCheck resources for health checking
-this RegionBackendService. Currently at most one health
-check can be specified, and a health check is required.`,
-				MinItems: 1,
-				MaxItems: 1,
-				Elem: &schema.Schema{
-					Type: schema.TypeString,
-				},
-				Set: selfLinkRelativePathHash,
-			},
 			"name": {
 				Type:     schema.TypeString,
 				Required: true,
@@ -378,6 +365,22 @@ This field is only used with l4 load balancing.`,
 					},
 				},
 			},
+			"health_checks": {
+				Type:     schema.TypeSet,
+				Optional: true,
+				Description: `The set of URLs to HealthCheck resources for health checking
+this RegionBackendService. Currently at most one health
+check can be specified. 
+
+A health check must be specified unless the backend service uses an internet
+or serverless NEG as a backend.`,
+				MinItems: 1,
+				MaxItems: 1,
+				Elem: &schema.Schema{
+					Type: schema.TypeString,
+				},
+				Set: selfLinkRelativePathHash,
+			},
 			"load_balancing_scheme": {
 				Type:         schema.TypeString,
 				Optional:     true,

website/docs/r/compute_backend_service.html.markdown

@@ -244,7 +244,8 @@ The following arguments are supported:
   The set of URLs to the HttpHealthCheck or HttpsHealthCheck resource
   for health checking this BackendService. Currently at most one health
   check can be specified.
-  A health check must be specified unless the backend service uses an internet NEG as a backend.
+  A health check must be specified unless the backend service uses an internet
+  or serverless NEG as a backend.
   For internal load balancing, a URL to a HealthCheck resource must be specified instead.
 
 * `iap` -

website/docs/r/compute_region_backend_service.html.markdown

@@ -213,12 +213,6 @@ resource "google_compute_subnetwork" "default" {
 The following arguments are supported:
 
 
-* `health_checks` -
-  (Required)
-  The set of URLs to HealthCheck resources for health checking
-  this RegionBackendService. Currently at most one health
-  check can be specified, and a health check is required.
-
 * `name` -
   (Required)
   Name of the resource. Provided by the client when the resource is
@@ -281,6 +275,14 @@ The following arguments are supported:
   Policy for failovers.
   Structure is documented below.
 
+* `health_checks` -
+  (Optional)
+  The set of URLs to HealthCheck resources for health checking
+  this RegionBackendService. Currently at most one health
+  check can be specified. 
+  A health check must be specified unless the backend service uses an internet
+  or serverless NEG as a backend.
+
 * `load_balancing_scheme` -
   (Optional)
   Indicates what kind of load balancing this regional backend service