connect contexts managed by fiber middleware to join at c.UserContext()

example/main.go

@@ -15,6 +15,7 @@ import (
 	"git.ma-al.com/maal-libraries/observer/pkg/level"
 	"github.com/gofiber/fiber/v2"
 	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
+	"go.opentelemetry.io/otel/trace"
 )
 
 func main() {
@@ -42,6 +43,9 @@ func main() {
 	main.Use(func(c *fiber.Ctx) error {
 		span := tracing.SpanFromContext(c)
 		span.AddEvent("pushed into a span an event from middleware")
+
+		span = trace.SpanFromContext(c.UserContext())
+		span.AddEvent("span also available from c.UserContext()")
 		return c.Next()
 	})