[Pigeon] Make java setup methods check for null arguments #57154

public static void setup(BinaryMessenger binaryMessenger, VideoPlayerApi api) {
      {
        BasicMessageChannel<Object> channel =
            new BasicMessageChannel<Object>(
                binaryMessenger,
                "dev.flutter.pigeon.VideoPlayerApi.initialize",
                new StandardMessageCodec());
        channel.setMessageHandler(
            new BasicMessageChannel.MessageHandler<Object>() {
              public void onMessage(Object message, BasicMessageChannel.Reply<Object> reply) {
                HashMap<String, HashMap> wrapped = new HashMap<String, HashMap>();
                try {
                  api.initialize();
                  wrapped.put("result", null);
                } catch (Exception exception) {
                  wrapped.put("error", wrapError(exception));
                }
                reply.reply(wrapped);
              }
            });
      }