public static Port parseProtocol(int port, String protocolString) {
    String protocol = UDP_PROTOCOL.equalsIgnoreCase(protocolString) ? UDP_PROTOCOL : TCP_PROTOCOL;
    return new Port(port, protocol);
  }
Gets a {@link Port} with protocol parsed from the string form {@code protocolString}. Unknown
protocols will default to TCP.

@param port the port number
@param protocolString the case insensitive string (e.g. "tcp", "udp")
@return the {@link Port}
jib-build-plan/src/main/java/com/google/cloud/tools/jib/api/buildplan/Port.java