why is graphql.servlet.tracing-enabled not working?

[KangSeongHyo]

Hi, im a junior developer and studying graphql hard. (My English isn’t very good, so please bear with me.)

it doesn't work. (I use playground)
application.yml
graphql.servlet.tracing-enabled : true

So
As an alternative, I created bean TracingInstrumentation

   @Bean
    public TracingInstrumentation tracingInstrumentation() {
        return new TracingInstrumentation(TracingInstrumentation.Options.newOptions().includeTrivialDataFetchers(true));
    }

This worked well
but I wonder why graphql.servlet.tracing-enabled is doesn't work Or Am i misunderstanding?

thank you