fix update jc user display name

jumpcloud/resource_user.go

@@ -226,13 +226,16 @@ func resourceUserUpdate(d *schema.ResourceData, m interface{}) error {
 	}
 
 	// Dynamically set the display name if there's a change
-	if d.HasChange("display_name") {
-		if displayName, ok := d.GetOk("display_name"); ok {
-			payload.Displayname = displayName.(string)
-		} else {
-			payload.Displayname = "" // Clear display name if not provided in the config
-		}
-	}
+    if d.HasChange("display_name") {
+        _, ok := d.GetOk("display_name")
+        if !ok {
+            // The attribute was removed from the configuration, so we explicitly clear it.
+            payload.Displayname = ""
+        } else {
+            // The attribute has a new value.
+            payload.Displayname = d.Get("display_name").(string)
+        }
+    }
 
 	req := map[string]interface{}{
 		"body": payload,