code: def format_relation_name(value, format_type=None):
      
      warnings.warn(
          "The 'format_relation_name' function has been renamed 'format_resource_type' and the "
          "settings are now 'JSON_API_FORMAT_TYPES' and 'JSON_API_PLURALIZE_TYPES' instead of "
          "'JSON_API_FORMAT_RELATION_KEYS' and 'JSON_API_PLURALIZE_RELATION_TYPE'",
          DeprecationWarning
      )
      if format_type is None:
          format_type = json_api_settings.FORMAT_RELATION_KEYS
      pluralize = json_api_settings.PLURALIZE_RELATION_TYPE
      return format_resource_type(value, format_type, pluralize)
docs: .. warning::
  
          The 'format_relation_name' function has been renamed 'format_resource_type' and the
          settings are now 'JSON_API_FORMAT_TYPES' and 'JSON_API_PLURALIZE_TYPES' instead of
          'JSON_API_FORMAT_RELATION_KEYS' and 'JSON_API_PLURALIZE_RELATION_TYPE'