message Outer {
	// As of: https://developers.google.com/protocol-buffers/docs/encoding#optional
	
	repeated Inner inner = 1;
	// "If your message definition has repeated elements (without the [packed=true] option), the encoded message has
	// zero or more key-value pairs with the same tag number."
	
}

message Inner {
	optional uint32 inner_value = 1;
}
