handle default req label for dynamic group better

docs/resources/dynamic_group.md

@@ -23,7 +23,7 @@ Dynamic Group resource manages Google Workspace Groups with Dynamic memberships.
 ### Optional
 
 - `description` (String) An extended description to help users determine the purpose of a group.For example, you can include information about who should join the group,the types of messages to send to the group, links to FAQs about the group, or related groups.
-- `labels` (Map of String) Defaults to `map[cloudidentity.googleapis.com/groups.discussion_forum:]`. One or more label entries that apply to the Group. Currently supported labels contain a key with an empty value.
+- `labels` (Map of String) One or more label entries that apply to the Group. Currently supported labels contain a key with an empty value.
 - `name` (String) The group's display name.
 - `timeouts` (Block, Optional) (see [below for nested schema](#nestedblock--timeouts))
 

internal/provider/resource_dynamic_group.go

@@ -98,7 +98,6 @@ func resourceDynamicGroup() *schema.Resource {
 				Type:        schema.TypeMap,
 				Optional:    true,
 				Elem:        &schema.Schema{Type: schema.TypeString},
-				Default:     map[string]interface{}{"cloudidentity.googleapis.com/groups.discussion_forum": ""},
 			},
 		},
 	}
@@ -123,9 +122,16 @@ func resourceDynamicGroupCreate(ctx context.Context, d *schema.ResourceData, met
 		return diags
 	}
 
-	labels, err := convertInterfaceMapToStringMap(d.Get("labels").(map[string]interface{}))
-	if err != nil {
-		return diag.FromErr(err)
+	labelsRaw, ok := d.GetOk("labels")
+	var labels map[string]string
+	if !ok || len(labelsRaw.(map[string]interface{})) == 0 {
+		labels = map[string]string{"cloudidentity.googleapis.com/groups.discussion_forum": ""}
+	} else {
+		var err error
+		labels, err = convertInterfaceMapToStringMap(labelsRaw.(map[string]interface{}))
+		if err != nil {
+			return diag.FromErr(err)
+		}
 	}
 
 	groupObj := cloudidentity.Group{