docs: def _plugins_inventory(self, entities):
          import os
          from ansible.plugins.loader import vars_loader
          from ansible.utils.vars import combine_vars
          ''' merges all entities by inventory source '''
          data = {}
          for inventory_dir in self.variable_manager._inventory._sources:
              if ',' in inventory_dir:  # skip host lists
                  continue
              elif not os.path.isdir(inventory_dir):  # always pass 'inventory directory'
                  inventory_dir = os.path.dirname(inventory_dir)
  
              for plugin in vars_loader.all():
                  data = combine_vars(data, self._get_plugin_vars(plugin, inventory_dir, entities))
          return data