See the "required is forever" warning here: https://developers.google.com/protocol-buffers/docs/proto https://developers.google.com/protocol-buffers/docs/proto

See the "required is forever" warning here: https://developers.google.com/protocol-buffers/docs/proto https://developers.google.com/protocol-buffers/docs/proto You may want to make even your conceptually required fields optional. As an example, if you tried to proxy a newer version of the protocol through an old proxy (assuming it's deserializing), unknown enumeration values for required fields could cause errors.