JSON objects in parsed with doublequotes (")

When using a JSON object in a zul page through data binding, the JSON object is parsed with double quotes (") which render it incorrect.

step to reproduce :
load the attached example
observe the source of the div, find the testjson attribute

value is similar to :
<div id="XXXXXX" class="z-div" testjson="

"=""><span id="XXXXXX" class="z-label">check this div attributes</span></div>

Data-handlers still work, but the resulting HTML is incorrect.