I've installed the LPCXpresso v8.2.2 IDE on Ubuntu 16.04 LTS and activated successfully, but I can't add the OpenOCD Debugging plugin to the IDE. I've tried writing the url in Help -> Install New Software... -> Work with, but I'm not getting any answer (just a "Pending..." sign):

I've tried with different Internet connections, so I don't believe that is the problem.