docs: def get_json(self):
          """Create JSON for CNA port.
  
          :returns: JSON for CNA port as follows:
              {
                  "@PortIdx":1,
                  "PortEnable":{
                  },
                  "Functions":{
                  }
              }
          """
          port = self.get_basic_json()
          port['Functions'] = {
              'Function': [f.get_json() for f in self.functions.values()]
          }
          return port