metadata property

The metadata provided here is included as part of the metadata_context (of type google.protobuf.Struct) in the ProcessingRequest message sent to the extension server.

The metadata applies to all extensions in all extensions chains in this resource. The metadata is available under the key com.google.lb_traffic_extension.. The following variables are supported in the metadata: {forwarding_rule_id} - substituted with the forwarding rule's fully qualified resource name. This field must not be set if at least one of the extension chains contains plugin extensions. Setting it results in a validation error. You can set metadata at either the resource level or the extension level. The extension level metadata is recommended because you can pass a different set of metadata through each extension to the backend.

Optional.

The values for Object must be JSON objects. It can consist of num, String, bool and null as well as Map and List values.