Update README.md

README.md

@@ -411,6 +411,8 @@ Below are listed some problems that may occur when attempting to use PF4J, and s
 See if you have a file `extensions.idx` in each plugin.  
 If file `extensions.idx` doesn't exist then probably it's something wrong with the annotation processing step (enable annotation processing in your IDE or in your Maven script).   
 If file `extensions.idx` exists and it's not empty then sure you have a class loader issue (you have the same extension point in two different class loader), in this situation you must remove some libraries (probably the API jar) from plugin.   
+If the problem persist or you want to find more info related to the extensions discovery process (e.g what interfaces/classes are loaded by each plugin, what classes are not recognized as extensions for an extension point) then you must put on `TRACE` level the logger for `PluginClassLoader` and `AbstractExtensionFinder` (see the [log4j.properties](https://github.com/decebals/pf4j/blob/master/demo/app/src/main/resources/log4j.properties) file for demo)   
+
 Are some resources on the internet related to this subject: [#82](https://github.com/decebals/pf4j/issues/82), [#64](https://github.com/decebals/pf4j/issues/64) and [No extensions found] (https://groups.google.com/forum/#!topic/pf4j/tEQXY_WpD3A).
 
 Demo