rsonvif: How to render metadata using onvifmetadataoverlay?

Hello,

I am creating an RTSP client which is going to display video and metadata
(as bounding boxes and some other text information) from an IP camera
supporting ONVIF profile M. I would like to use rsonvif plugins.
I am able to display video as well as display/save metadata as XML using
for example:

gst-launch-1.0 rtspsrc location=rtsp:// user:password@ip/rtsp/xxxx name=t
t. ! queue ! application/x-rtp, media=video,
clock-rate=90000,encoding-name=H264 ! rtph264depay ! avdec_h264 !
videoconvert ! glimagesink sync=false t. ! queue ! application/x-rtp,
media=application ! filesink location=data.txt
I would like to use onvifmetadataoverlay to display metadata over video but
I don't know how to do it. Do you have any examples of working pipelines
with onvifmetadataoverlay?

Many thanks!