Downgrade level of logging message

Author: geoand

opentracing-spring-tracer-configuration-starter/src/main/java/io/opentracing/contrib/spring/tracer/configuration/TracerAutoConfiguration.java

@@ -1,5 +1,5 @@
 /**
- * Copyright 2018 The OpenTracing Authors
+ * Copyright 2018-2019 The OpenTracing Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -61,7 +61,7 @@ public Tracer getTracer() {
         tracer = NoopTracerFactory.create();
       }
     }
-    log.warn("Tracer bean is not configured! Switching to " + tracer);
+    log.debug("Tracer bean is not configured! Switching to " + tracer);
     return tracer;
   }
 }