DocumentId id() {
            return new DocumentId("id:" + requireNonNull(path.get("namespace")) +
                                  ":" + requireNonNull(path.get("documentType")) +
                                  ":" + group.map(Group::docIdPart).orElse("") +
                                  ":" + String.join("/", requireNonNull(path.getRest()).segments())); // :'(
        }
Returns the last property with the given name, if present, or throws if this is empty or blank.
vespaclient-container-plugin/src/main/java/com/yahoo/document/restapi/resource/DocumentV1ApiHandler.java