How to change the security group of an existing server in openstack via jclouds?

[bat desso]

 Hi all,  
  Can you please help me with this topic - I would like to do the following – I 
want to change the security group of an existing server in openstack.  I could 
not find any documentation how to do that using jclouds. 
Which API I need to use?  
  Best regards - batdesso