This exception is being thrown by
org.jclouds.compute.ComputeService.suspendNodesMatching method with
Openstack provider. My question is - what does it mean? Where should
I install these extensions, i.e. is it about installing something
in Openstack or about adding a library dependency in the code?
I suspect this is indeed something that needs to be
installed/configured in your OpenStack installation:
http://docs.openstack.org/api/openstack-compute/2/content/ext-action.html
You could try to reproduce this, if desired, by calling one of the
admin actions directly (e.g. using cURL) to see what the response code
is.
Regards
ap