nkatsar/logback-XSD — pull request #1 by rtack (2014-12-20 18:20:53+00:00)
Title: add optional attribute to Include type

see http://logback.qos.ch/manual/configuration.html

If it cannot find the file to be included, logback will complain by printing a status message. In case the included file is optional, you can suppress the error message by setting optional attribute to true in the element.