How to Free resources in gst-rtsp-server ?

[yangsb]

Hi ,guys.
I used gst-rtsp-server for several months.
Now , I found that some resource can't be free correctly .
I checked the code in gst-launch.c , and found that there is such code to free resources:
******************************************************
gst_element_set_state ( pipeline, GST_STATE_NULL )；
******************************************************
However , in gst-rtsp-server/examples/test-launch.c ，there isn't any such codes.
So, is there any api in gst-rtsp-server that can be used to free resources ?
I think this is very useful .

Thanks.
Best regards.