static ExecutorService makeContextPropagating(ExecutorService executor) {
        return PropagatingContextAwareExecutorService.of(executor);
    }
Returns an {@link ExecutorService} that will execute callbacks in the given {@code executor}, propagating
the caller's {@link RequestContext} (if any) into the callback execution.
If this executor service is only used from a single request then it's better to use
{@link #makeContextAware(ExecutorService)}
core/src/main/java/com/linecorp/armeria/common/RequestContext.java