public XMLWriter content(Object content,boolean multiline) {
        closeStartTag();
        return (content==null)
                ? this
                : escapedContent(XML.xmlEscape(content.toString(),false),multiline);
    }
XML escapes and writes the content.toString(). If the content is null this does nothing but closing the start tag.

@param content the content - output by XML.xmlEscape(content.toString())
@param multiline whether the content should be treated as multiline,
       such that the following end tag should appear on a new line
vespajlib/src/main/java/com/yahoo/text/XMLWriter.java