Currently if log4jRefreshInterval is empty, Log4jWebConfigurer throws an exception because the value is not a number. Consider the following scenario when value is substituted by Maven (resource filtering = true):
If log4j.refresh.interval is empty, application does not start. The solution is either to set log4j.refresh.interval to big value like 9999999, or do some fuzzy things in Maven POM to juggle two different web.xml files.
Log4jWebConfigurer should treat empty refresh interval as not-defined.