Fix firewall rule to support empty descritpion on update

mmv1/products/compute/Firewall.yaml

@@ -167,6 +167,7 @@ properties:
     description: |
       An optional description of this resource. Provide this property when
       you create the resource.
+    send_empty_value: true
   - !ruby/object:Api::Type::Array
     name: 'destinationRanges'
     description: |

mmv1/third_party/terraform/services/compute/resource_compute_firewall_test.go.erb

@@ -37,6 +37,17 @@ func TestAccComputeFirewall_update(t *testing.T) {
 				ImportState:       true,
 				ImportStateVerify: true,
 			},
+			{
+				Config: testAccComputeFirewall_nullDescription(networkName, firewallName),
+				Check: resource.ComposeTestCheckFunc(
+					resource.TestCheckResourceAttr("google_compute_firewall.foobar", "description", ""),
+				),
+			},
+			{
+				ResourceName:      "google_compute_firewall.foobar",
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
 			{
 				Config: testAccComputeFirewall_basic(networkName, firewallName),
 			},
@@ -392,6 +403,29 @@ resource "google_compute_firewall" "foobar" {
 `, network, firewall)
 }
 
+func testAccComputeFirewall_nullDescription(network, firewall string) string {
+	return fmt.Sprintf(`
+resource "google_compute_network" "foobar" {
+  name                    = "%s"
+  auto_create_subnetworks = false
+}
+
+resource "google_compute_firewall" "foobar" {
+  name        = "%s"
+  description = null
+  network     = google_compute_network.foobar.self_link
+  source_tags = ["foo"]
+  target_tags = ["bar"]
+
+  allow {
+    protocol = "tcp"
+    ports    = ["80-255"]
+  }
+}
+`, network, firewall)
+}
+
+
 func testAccComputeFirewall_priority(network, firewall string, priority int) string {
 	return fmt.Sprintf(`
 resource "google_compute_network" "foobar" {

mmv1/third_party/tgc/tests/data/example_compute_firewall.json

@@ -22,6 +22,7 @@
             ]
           }
         ],
+        "description": "",
         "disabled": false,
         "logConfig": {
           "enable": false

mmv1/third_party/tgc/tests/data/firewall.json

@@ -22,6 +22,7 @@
             ]
           }
         ],
+        "description": "",
         "disabled": false,
         "logConfig": {
           "enable": false

mmv1/third_party/tgc/tests/data/full_compute_firewall.json

@@ -65,6 +65,7 @@
             ]
           }
         ],
+        "description": "",
         "disabled": false,
         "logConfig": {
           "enable": false
@@ -102,6 +103,7 @@
             "IPProtocol": "icmp"
           }
         ],
+        "description": "",
         "disabled": false,
         "logConfig": {
           "enable": false