Replacing Advice.class references with string construction.
This stops the JVM from loading the Advice classes which are used as templates for byte buddy and doesn't ever need to be run directly.
This eliminates ~130 class loads at start-up -- and saves 0.5MiB in metaspace
Sometimes servlets will call another servlet by “resetting” the request object. This maintains the attributes previously set, including the span. We want to allow the trace to start if there’s no “active trace” even if there is a span attribute.
Trask Stalnaker