code: func AgentMetadataHandler(containerInstanceArn *string, cfg *config.Config) func(http.ResponseWriter, *http.Request) {
  	return func(w http.ResponseWriter, r *http.Request) {
  		resp := &MetadataResponse{
  			Cluster:              cfg.Cluster,
  			ContainerInstanceArn: containerInstanceArn,
  			Version:              agentversion.String(),
  		}
  		responseJSON, _ := json.Marshal(resp)
  		utils.WriteJSONToResponse(w, http.StatusOK, responseJSON, utils.RequestTypeAgentMetadata)
  	}
  }
docs: // AgentMetadataHandler creates response for 'v1/metadata' API.