The docs for MarkupGrid state that to create sections a ContentNode with a contentType of "SECTION" should be created, with the item or content nodes contained as children of the section node. However, attempting to set the contentType to "SECTION" on a ContentNode returns the error "Error setting the "ContentType" field of a "ContentNode" node".
I believe that this is because a contentNode's ContentType can only be set to certain pre-defined strings (from the Docs for ContentNode: "Valid values = movie, episode, season, series, audio"). If that is the case, how can sections be created for a MarkupGrid?