Define the class for governing x-goog-request-params metadata value.
The value of x-goog-request-params starts with one of the following suffix "parent=" : Operation in instance, e.g. TableAdmin::CreateTable. "table_name=" : table_id is known at the time of creation, e.g. Table::Apply. "name=" : this is used when table|_id is known only in the RPC call, e.g. TableAdmin::GetTable. "resource=" : this is used to set IAM policies for bigtable resource.
The Setup function also adds x-goog-api-client header for analytics purpose.
