fix(vm): regression: vga.clipboard attribute check (#1340)

Signed-off-by: Pavel Boldyrev <627562+bpg@users.noreply.github.com>

example/resource_virtual_environment_vm.tf

@@ -107,6 +107,10 @@ resource "proxmox_virtual_environment_vm" "example_template" {
 
   serial_device {}
 
+  vga {
+    type = "qxl"
+  }
+
   template = true
 
   // use auto-generated vm_id

fwprovider/test/resource_vm_test.go

@@ -175,7 +175,8 @@ func TestAccResourceVM(t *testing.T) {
 				}`),
 				Check: resource.ComposeTestCheckFunc(
 					ResourceAttributes("proxmox_virtual_environment_vm.test_vm", map[string]string{
-						"vga.0.type": "none",
+						"vga.0.type":      "none",
+						"vga.0.clipboard": "",
 					}),
 				),
 			}, {
@@ -195,6 +196,23 @@ func TestAccResourceVM(t *testing.T) {
 						"vga.0.clipboard": "vnc",
 					}),
 				),
+			}, {
+				Config: te.RenderConfig(`
+				resource "proxmox_virtual_environment_vm" "test_vm" {
+					node_name = "{{.NodeName}}"
+					started   = false
+					
+					vga {
+						type = "virtio-gl"
+						clipboard = ""
+					}
+				}`),
+				Check: resource.ComposeTestCheckFunc(
+					ResourceAttributes("proxmox_virtual_environment_vm.test_vm", map[string]string{
+						"vga.0.type":      "virtio-gl",
+						"vga.0.clipboard": "",
+					}),
+				),
 			}},
 		},
 	}

fwprovider/vm/vga/resource_test.go

@@ -66,6 +66,9 @@ func TestAccResourceVM2VGA(t *testing.T) {
 						"vga.type":   "std",
 						"vga.memory": "16",
 					}),
+					test.NoResourceAttributesSet("proxmox_virtual_environment_vm2.test_vm", []string{
+						"vga.clipboard",
+					}),
 				),
 			},
 			{ // now update the vga params and check if they are updated

proxmoxtf/resource/vm/vm.go

@@ -1403,6 +1403,7 @@ func VM() *schema.Resource {
 						Optional:    true,
 						Default:     dvVGAClipboard,
 						ValidateDiagFunc: validation.ToDiagFunc(validation.StringInSlice([]string{
+							"",
 							"vnc",
 						}, true)),
 					},