public static void main(String[] args) {
Yaml yaml = new Yaml();
InputStream resourceAsStream =
ClassLoader.getSystemClassLoader().getResourceAsStream("hello_world_app_spec.yaml");
HelloworldAppSpec spec = yaml.loadAs(resourceAsStream, HelloworldAppSpec.class);
String dump = yaml.dump(spec);
System.out.println(dump);
System.out.println(spec.getServiceConfig("HelloWorld").getStringField("num_containers", "1"));
}