That’s not standard CommonMark. I’m surprised that Atlassian is publishing their Java CommonMark library under the auspices of “org.commonmark”, which seems to me misleading people to believe that this library is official and produced by CommonMark.org. //cc @jgm @codinghorror Perhaps I make a minor quibble?
@pdesjardins, My guess is you should look at the Atlassian extensions for their library, specifically: https://github.com/atlassian/commonmark-java#image-attributes