Official Polymer compatibility

- Based on my PolymerRocks compatibility patch, featuring many improvements over it
- Less hardcoded object instances, allowing for easier addition of new variations

src/main/java/eu/midnightdust/motschen/rocks/networking/HelloPayload.java

@@ -0,0 +1,24 @@
+package eu.midnightdust.motschen.rocks.networking;
+
+import eu.midnightdust.motschen.rocks.RocksMain;
+import net.minecraft.network.RegistryByteBuf;
+import net.minecraft.network.codec.PacketCodec;
+import net.minecraft.network.packet.CustomPayload;
+import net.minecraft.util.Identifier;
+
+public record HelloPayload() implements CustomPayload {
+    public static final Identifier hello = RocksMain.id("hello_payload");
+    public static final CustomPayload.Id<HelloPayload> PACKET_ID = new CustomPayload.Id<>(hello);
+    public static final PacketCodec<RegistryByteBuf, HelloPayload> codec = PacketCodec.of(HelloPayload::write, HelloPayload::read);
+
+    public static HelloPayload read(RegistryByteBuf buf) {
+        return new HelloPayload();
+    }
+
+    public void write(RegistryByteBuf buf) {}
+
+    @Override
+    public Id<? extends CustomPayload> getId() {
+        return PACKET_ID;
+    }
+}