A NegotiateProtocolVersion packet may be sent by the server when a client connects to ask the client to use a different version of the protocol.
See the Postgres documentation for details.
String packetType: "NegotiateProtocolVersion"
int newestSupportedMinor: the latest minor version.
List<String> optionsNotRecognized() : the list of options not recognized by the server. This list may be empty, and it can be changed.