After fixing the validation error in my Ant build.xml files, I got to wondering about the other common XML files in my projects. I’ve used Logback on many of my recent projects and it’s configuration has similar warnings that can be resolved in the same manner.
The simplest method to silence the warning is to add a DOCTYPE to the logback.xml files, between the XML declaration and the configuration. Official documentation seems to indicate that a DTD is not possible or likely.
<?xml version="1.0" encoding="UTF-8"?>
NOTE: For what it’s worth, this approach should work for any XML file to remove the error in Eclipse.