mvn xar:format does not properly remove comment content

The content of comment is not properly cleaned up by mvn xar:format.

Reproduction step:

• unzip the provided example, go in the folder and execute mvn xar:format

Expected result:

• the WebHome.xml file should contain <comment/> and calling mvn clean install should success

Obtained result:

• the WebHome.xml file contains <comment>]</comment> and mvn clean install fail because of it.