docs: def get_essential_properties(self):
          """Constructs the dictionary of essential properties
  
          Constructs the dictionary of essential properties, named
          cpu, cpu_arch, local_gb, memory_mb. The MACs are also returned
          as part of this method.
          """
          sushy_system = self._get_sushy_system(PROLIANT_SYSTEM_ID)
          try:
              # TODO(nisha): Add local_gb here and return after
              # local_gb changes are merged.
              # local_gb = sushy_system.storage_summary
              prop = {'memory_mb': (sushy_system.memory_summary.size_gib * 1024),
                      'cpus': sushy_system.processors.summary.count,
                      'cpu_arch': sushy_map.PROCESSOR_ARCH_VALUE_MAP_REV.get(
                      sushy_system.processors.summary.architecture),
                      'local_gb': common_storage.get_local_gb(sushy_system)}
              return {'properties': prop,
                      'macs': sushy_system.ethernet_interfaces.summary}
          except sushy.exceptions.SushyError as e:
              msg = (self._('The Redfish controller failed to get the '
                            'resource data. Error %(error)s')
                     % {'error': str(e)})
              LOG.debug(msg)
              raise exception.IloError(msg)