GWT 2.6 Предупреждения консоли

Question

Что означают эти предупреждения?

[WARN] Server class 'org.eclipse.jetty.servlet.listener.ELContextCleaner' could not be found in the web app, but was found on the system classpath 
    [WARN] Adding classpath entry 'file:/Applications/gwt/gwt-2.6.0/gwt-dev.jar' to the web app classpath for this session 
    For additional info see: file:/Applications/gwt/gwt-2.6.0/doc/helpInfo/webAppClassPath.html 
[WARN] Server class 'org.slf4j.Logger' could not be found in the web app, but was found on the system classpath 
    [WARN] Adding classpath entry 'file:/Users/mg/Documents/Grails/GGTS3.5M1/buddyis/lib/gwt/slf4j-api-1.7.5.jar' to the web app classpath for this session 
    For additional info see: file:/Applications/gwt/gwt-2.6.0/doc/helpInfo/webAppClassPath.html 
[WARN] Server class 'org.slf4j.impl.StaticLoggerBinder' could not be found in the web app, but was found on the system classpath 
    [WARN] Adding classpath entry 'file:/Users/mg/Documents/Grails/GGTS3.5M1/buddyis/lib/gwt/mobile/slf4j-log4j12-1.7.5.jar' to the web app classpath for this session 
    For additional info see: file:/Applications/gwt/gwt-2.6.0/doc/helpInfo/webAppClassPath.html 
[WARN] Server class 'org.apache.log4j.Level' could not be found in the web app, but was found on the system classpath 
    [WARN] Adding classpath entry 'file:/Users/mg/Documents/Grails/GGTS3.5M1/buddyis/lib/gwt/mobile/log4j-1.2.17.jar' to the web app classpath for this session 
    For additional info see: file:/Applications/gwt/gwt-2.6.0/doc/helpInfo/webAppClassPath.html 
log4j:WARN No appenders could be found for logger (org.eclipse.jetty.util.log). 
log4j:WARN Please initialize the log4j system properly. 
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info. 
log4j:WARN No appenders could be found for logger (org.apache.jasper.compiler.JspRuntimeContext). 
log4j:WARN Please initialize the log4j system properly. 
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info. 

Answer 1

Первый набор предупреждения будет, потому что при запуске DEV-режиме, он начинает сервлет контейнер (Jetty), которая по умолчанию настроена использовать любую библиотеку в вашем пути к классам проекта, когда происходит класс-не обретенной , Эти предупреждения полезны, чтобы знать, какие библиотеки вы должны добавить к вашему артефакту .war в процессе производства.

Второй комплект WARNings - это то, что вы еще не настроили log4j для своего проекта.