def activity_entities_for_model(model_class)
      @activity_entities_for_model[model_class] ||= begin
        result = [ ]

        @entity_classes.each do |entity_name, entity_class|
          result << entity_name if (entity_class == model_class)
        end

        result
      end
    end
def activity_entities_for_model(model_class)
      @activity_entities_for_model[model_class] ||= begin
        result = [ ]

        @entity_classes.each do |entity_name, entity_class|
          result << entity_name if (entity_class == model_class)
        end

        result
      end
    end
Get all entities names for given model class