Introduce log4j and turn it off to disable logging and meet PF4J requirements

app/build.gradle

@@ -4,6 +4,8 @@ dependencies {
     compile group: 'org.jetbrains.kotlin', name: 'kotlin-reflect', version: '1.3.61'
     testCompile group: 'junit', name: 'junit', version: '4.12'
     compile group: 'org.pf4j', name: 'pf4j', version: '3.2.0'
+    compile group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.13.1'
+    compile group: 'org.slf4j', name: 'slf4j-log4j12', version: '2.0.0-alpha1'
 }
 
 jar {

app/src/main/resources/log4j.properties

@@ -0,0 +1,16 @@
+log4j.rootLogger=OFF, Console
+
+# PF4J log
+log4j.logger.org.pf4j=OFF, Console
+# !!! Put the bellow classes on level TRACE when you are in trouble
+log4j.logger.org.pf4j.PluginClassLoader=OFF, Console
+log4j.logger.org.pf4j.AbstractExtensionFinder=OFF, Console
+log4j.additivity.org.pf4j=false
+log4j.additivity.org.pf4j.PluginClassLoader=false
+log4j.additivity.org.pf4j.AbstractExtensionFinder=false
+
+# Appenders
+log4j.appender.Console=org.apache.log4j.ConsoleAppender
+log4j.appender.Console.layout=org.apache.log4j.PatternLayout
+#log4j.appender.Console.layout.conversionPattern=%-5p - %-32.32c{1} - %m\n
+log4j.appender.Console.layout.ConversionPattern=%d %p %c - %m%n