HtmlCleaner seems to not knowing the tag, and it drop it when it is told to drop unknown tags. I have checked the following with the command line of htmlcleaner:
Therefore:
test
content
became using java -jar htmlcleaner-2.1.jar src=(above sample in a file) omitunknowntags=true
According to XML specs double hyphen inside comments need to be escaped and since there is a specific method to write comment I guess it can be done somewhere around it. A crappy quick fix would be text.replaceAll("--", "--") but i'm sure you have a better solution ;)
