public XMLWriter attribute(String name, Object value) {
        if (value==null) return this;
        return attribute(new Utf8String(name), value.toString());
    }
Writes an attribute by XML.xmlEscape(value.toString(),false)

@param name the name of the attribute. An exception is thrown if this is null
@param value the value of the attribute. This method does nothing if the value is null or empty
vespajlib/src/main/java/com/yahoo/text/XMLWriter.java