Skip serialization for empty fields

src/main.rs

@@ -42,8 +42,11 @@ struct Cli {
 
 #[derive(Serialize)]
 struct MessageMap {
+    #[serde(skip_serializing_if = "Option::is_none")]
     server_id: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     domain_name_servers: Option<Vec<String>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     domain_search_list: Option<Vec<String>>,
 }