java - vertx LoggerHandler not adding logback -

i trying use loggerhandler log incoming requests. using logback.xml specify appenders. setting system property logging.

system.setproperty("org.vertx.logger-delegate-factory-class-name",             "org.vertx.java.core.logging.impl.slf4jlogdelegatefactory"); 

still logging in console not in file.

this worked me vert.x 3.4.1:

    import static io.vertx.core.logging.loggerfactory.logger_delegate_factory_class_name;     import io.vertx.core.logging.loggerfactory;      // ...      setproperty (logger_delegate_factory_class_name, slf4jlogdelegatefactory.class.getname ());     loggerfactory.getlogger (loggerfactory.class); // required logback work in vertx 

the key logger, guess initializes logging subsystem, class use logger seems irrelevant tried 2 different ones.

i run these lines first ones of program in production code and in tests work in both contexts.