I did a whole lot, essentially added a whole property system. (sorry for not commiting, i forgot)

common/src/main/java/me/zimzaza4/geyserutils/common/packet/EntityPropertyPacket.java

@@ -0,0 +1,18 @@
+package me.zimzaza4.geyserutils.common.packet;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+@Setter
+@Getter
+@AllArgsConstructor
+@NoArgsConstructor
+public class EntityPropertyPacket<T> extends CustomPayloadPacket {
+    private int entityId;
+
+    private String identifier;
+    private T value;
+
+}

common/src/main/java/me/zimzaza4/geyserutils/common/packet/EntityPropertyRegisterPacket.java

@@ -0,0 +1,18 @@
+package me.zimzaza4.geyserutils.common.packet;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+@Setter
+@Getter
+@AllArgsConstructor
+@NoArgsConstructor
+public class EntityPropertyRegisterPacket extends CustomPayloadPacket {
+    private int entityId;
+
+    private String identifier;
+    private Class<?> type;
+
+}

geyser/src/main/java/me/zimzaza4/geyserutils/geyser/GeyserUtils.java

@@ -45,6 +45,7 @@ import org.geysermc.geyser.api.skin.Skin;
 import org.geysermc.geyser.api.skin.SkinData;
 import org.geysermc.geyser.api.skin.SkinGeometry;
 import org.geysermc.geyser.entity.EntityDefinition;
+import org.geysermc.geyser.entity.properties.GeyserEntityProperties;
 import org.geysermc.geyser.entity.type.Entity;
 import org.geysermc.geyser.entity.type.player.PlayerEntity;
 import org.geysermc.geyser.inventory.GeyserItemStack;
@@ -94,13 +95,19 @@ public class GeyserUtils implements Extension {
     public static ItemParticlesMappings particlesMappings = new ItemParticlesMappings();
     static Cape EMPTY_CAPE = new Cape("", "no-cape", ByteArrays.EMPTY_ARRAY, true);
 
-
-
     public static final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(2);
 
+    private static final Map<String, List<Map.Entry<String, Class<?>>>> properties = new HashMap<>();
+
+    @Getter
+    private static GeyserUtils instance;
+
+    public GeyserUtils() {
+        instance = this;
+    }
+
     @Subscribe
     public void onEnable(GeyserPostInitializeEvent event) {
-
         Registries.BEDROCK_PACKET_TRANSLATORS.register(NpcRequestPacket.class, new NPCFormResponseTranslator());
         loadSkins();
         ReflectionUtils.init();
@@ -115,6 +122,60 @@ public class GeyserUtils implements Extension {
         particlesMappings.read(dataFolder().resolve("item_particles_mappings.json"));
     }
 
+    // the static here is crazy ;(
+    private static GeyserEntityProperties getProperties(String id) {
+        if (!properties.containsKey(id)) return null;
+
+        GeyserEntityProperties.Builder builder = new GeyserEntityProperties.Builder();
+        List<Map.Entry<String, Class<?>>> pairs = properties.get(id);
+        pairs.forEach(p -> {
+            // only bool, float and int support for now
+            if (p.getValue() == Boolean.class) builder.addBoolean(p.getKey());
+            else if (p.getValue() == Float.class) builder.addBoolean(p.getKey());
+            else if (p.getValue() == Integer.class) builder.addBoolean(p.getKey());
+            else instance.logger().info("Found unknown property: " + p.getKey());
+        });
+
+        return builder.build();
+    }
+
+    private static boolean containsProperty(String entityId, String identifier) {
+        if (!properties.containsKey(entityId)) return false;
+
+        return properties.get(entityId).stream().anyMatch(p -> p.getKey().equalsIgnoreCase(identifier));
+    }
+
+    public static void addProperty(String entityId, String identifier, Class<?> type) {
+        if (containsProperty(entityId, identifier)) return;
+
+        List<Map.Entry<String, Class<?>>> pairs = properties.getOrDefault(entityId, new ArrayList<>());
+        pairs.add(new AbstractMap.SimpleEntry<>(identifier, type));
+
+        if (properties.containsKey(entityId)) properties.replace(entityId, pairs);
+        else properties.put(entityId, pairs);
+    }
+
+    public static void registerProperties(String entityId) {
+        GeyserEntityProperties entityProperties = getProperties(entityId);
+        if (entityProperties == null) return;
+
+        properties.values().stream()
+                .flatMap(List::stream)
+                .map(Map.Entry::getKey)
+                .forEach(id -> {
+                    Registries.BEDROCK_ENTITY_PROPERTIES.get().removeIf(i -> i.containsKey(id));
+                });
+
+
+        Registries.BEDROCK_ENTITY_PROPERTIES.get().add(entityProperties.toNbtMap(entityId));
+
+        EntityDefinition old = LOADED_ENTITY_DEFINITIONS.get(entityId);
+        LOADED_ENTITY_DEFINITIONS.replace(entityId, new EntityDefinition(old.factory(), old.entityType(), old.identifier(),
+                old.width(), old.height(), old.offset(), entityProperties, old.translators()));
+
+        instance.logger().info("Defined property: " + entityId + " in registry.");
+    }
+
     public static void addCustomEntity(String id) {
         /*
         LOADED_ENTITY_DEFINITIONS.put(id,
@@ -140,7 +201,9 @@ public class GeyserUtils implements Extension {
         Registries.BEDROCK_ENTITY_IDENTIFIERS.set(NbtMap.builder()
                 .putList("idlist", NbtType.COMPOUND, idList).build()
         );
-        EntityDefinition<Entity> def = EntityDefinition.builder(null).height(0.1f).width(0.1f).identifier(id).build();
+
+        EntityDefinition<Entity> def = EntityDefinition.builder(null)
+                .height(0.1f).width(0.1f).identifier(id).registeredProperties(getProperties(id)).build();
 
         LOADED_ENTITY_DEFINITIONS.put(id, def);
     }
@@ -356,6 +419,45 @@ public class GeyserUtils implements Extension {
                                    if (customEntityDataPacket.getScale() != null) entity.getDirtyMetadata().put(EntityDataTypes.SCALE, customEntityDataPacket.getScale());
                                    entity.updateBedrockMetadata();
                                }
+                           } else if (customPacket instanceof EntityPropertyPacket entityPropertyPacket) {
+                               Entity entity = (session.getEntityCache().getEntityByJavaId(entityPropertyPacket.getEntityId()));
+                               if (entity != null) {
+                                   if (entityPropertyPacket.getIdentifier() == null
+                                           || entityPropertyPacket.getValue() == null) return;
+
+                                   String def = CUSTOM_ENTITIES.get(session).getIfPresent(entity.getEntityId());
+                                   if (def == null) return;
+
+                                   if (!containsProperty(def, entityPropertyPacket.getIdentifier())) {
+                                       addProperty(def, entityPropertyPacket.getIdentifier(), entityPropertyPacket.getValue().getClass());
+
+                                       registerProperties(def);
+                                   }
+
+                                   if (entity.getPropertyManager() == null) return;
+                                   entity.getPropertyManager().add(entityPropertyPacket.getIdentifier(),
+                                           (Boolean) entityPropertyPacket.getValue());
+
+                                   entity.updateBedrockEntityProperties();
+                               }
+                           } else if (customPacket instanceof EntityPropertyRegisterPacket entityPropertyRegisterPacket) {
+                               if (entityPropertyRegisterPacket.getIdentifier() == null
+                                       || entityPropertyRegisterPacket.getType() == null) return;
+
+                               Entity entity = (session.getEntityCache().getEntityByJavaId(entityPropertyRegisterPacket.getEntityId()));
+                               if (entity != null) {
+                                   String def = CUSTOM_ENTITIES.get(session).getIfPresent(entity.getEntityId());
+                                   if (def == null) return;
+
+                                   if (!containsProperty(def, entityPropertyRegisterPacket.getIdentifier())) {
+                                       addProperty(def, entityPropertyRegisterPacket.getIdentifier(), entityPropertyRegisterPacket.getType());
+
+                                       registerProperties(def);
+                                       logger().info("Defined property: " + entityPropertyRegisterPacket.getIdentifier() + " in registry.");
+                                   }
+                               }
+
+
                            } else if (customPacket instanceof CustomEntityPacket customEntityPacket) {
                                if (!LOADED_ENTITY_DEFINITIONS.containsKey(customEntityPacket.getIdentifier())) {
                                    return;

geyser/src/main/java/me/zimzaza4/geyserutils/geyser/replace/JavaAddEntityTranslatorReplace.java

@@ -25,6 +25,7 @@
 
 package me.zimzaza4.geyserutils.geyser.replace;
 
+import org.geysermc.geyser.entity.properties.GeyserEntityPropertyManager;
 import org.geysermc.mcprotocollib.protocol.data.game.entity.metadata.Pose;
 import org.geysermc.mcprotocollib.protocol.data.game.entity.object.Direction;
 import org.geysermc.mcprotocollib.protocol.data.game.entity.object.FallingBlockData;
@@ -44,6 +45,8 @@ import org.geysermc.geyser.text.GeyserLocale;
 import org.geysermc.geyser.translator.protocol.PacketTranslator;
 import org.geysermc.geyser.translator.protocol.Translator;
 
+import java.lang.reflect.Field;
+
 import static me.zimzaza4.geyserutils.geyser.GeyserUtils.CUSTOM_ENTITIES;
 import static me.zimzaza4.geyserutils.geyser.GeyserUtils.LOADED_ENTITY_DEFINITIONS;
 
@@ -127,8 +130,15 @@ public class JavaAddEntityTranslatorReplace extends PacketTranslator<Clientbound
 
         String def = CUSTOM_ENTITIES.get(session).getIfPresent(entity.getEntityId());
         if (def != null) {
-            // System.out.println("CUSTOM ENTITY :" + event.entityId() + " | " + def);
+            System.out.println("CUSTOM ENTITY :" + entity.getEntityId() + " | " + def);
-            entity.setDefinition(LOADED_ENTITY_DEFINITIONS.getOrDefault(def, entity.getDefinition()));
+
+            EntityDefinition newDef = LOADED_ENTITY_DEFINITIONS.getOrDefault(def, entity.getDefinition());
+            System.out.println("CUSTOM DEF : " + newDef);
+            entity.setDefinition(newDef);
+
+            // reinstantiate the entity object to create the propertymanager.
+            entity = new Entity(entity.getSession(), entity.getEntityId(), entity.getGeyserId(), entity.getUuid(),
+                    entity.getDefinition(), entity.getPosition(), entity.getMotion(), yaw, pitch, headYaw);
         }
 
         session.getEntityCache().spawnEntity(entity);

geyser/src/main/java/me/zimzaza4/geyserutils/geyser/util/ReflectionUtils.java

@@ -31,11 +31,7 @@ public class ReflectionUtils {
     @SneakyThrows
     public static void init() {
         PlatformType type = GeyserImpl.getInstance().platformType();
-        if (type == PlatformType.STANDALONE) {
+        prefix = type == PlatformType.STANDALONE || type == PlatformType.VELOCITY ? "" : "org.geysermc.geyser.platform." + type.platformName().toLowerCase() + ".shaded.";
-            prefix = "";
-        } else {
-            prefix = "org.geysermc.geyser.platform." + type.platformName().toLowerCase() + ".shaded.";
-        }
         CLIENTBOUND_PAYLOAD_PACKET_CLASS = ClientboundCustomPayloadPacket.class;
         SERVERBOUND_PAYLOAD_PACKET_CLASS = ServerboundCustomPayloadPacket.class;
         KEY_CLASS = Class.forName(prefix + "net.kyori.adventure.key.Key");

spigot/pom.xml

@@ -61,6 +61,10 @@
             <id>sonatype</id>
             <url>https://oss.sonatype.org/content/groups/public/</url>
         </repository>
+        <repository>
+            <id>opencollab-snapshot</id>
+            <url>https://repo.opencollab.dev/main/</url>
+        </repository>
     </repositories>
 
     <dependencies>

spigot/src/main/java/me/zimzaza4/geyserutils/spigot/api/PlayerUtils.java

@@ -7,6 +7,7 @@ import me.zimzaza4.geyserutils.common.packet.*;
 import me.zimzaza4.geyserutils.common.particle.CustomParticle;
 import me.zimzaza4.geyserutils.common.util.Pos;
 import me.zimzaza4.geyserutils.spigot.GeyserUtils;
+import org.bukkit.Bukkit;
 import org.bukkit.Location;
 import org.bukkit.entity.Entity;
 import org.bukkit.entity.Player;
@@ -88,4 +89,38 @@ public class PlayerUtils {
         player.sendPluginMessage(GeyserUtils.getInstance(), GeyserUtilsChannels.MAIN, GeyserUtils.getPacketManager().encodePacket(packet));
 
     }
+
+    // (yes I'm aware it's "horrible" code, I'm just matching the energy of this plugin), also this aint player packets at all lmao
+
+    public static void registerProperty(Player player, Entity entity, String identifier, Class<?> type) {
+        EntityPropertyRegisterPacket packet = new EntityPropertyRegisterPacket();
+        packet.setEntityId(entity.getEntityId());
+        packet.setIdentifier(identifier);
+        packet.setType(type);
+        player.sendPluginMessage(GeyserUtils.getInstance(), GeyserUtilsChannels.MAIN, GeyserUtils.getPacketManager().encodePacket(packet));
+    }
+
+    public static void sendBoolProperty(Player player, Entity entity, String identifier, Boolean value) {
+        EntityPropertyPacket<Boolean> packet = new EntityPropertyPacket<>();
+        packet.setEntityId(entity.getEntityId());
+        packet.setIdentifier(identifier);
+        packet.setValue(value);
+        player.sendPluginMessage(GeyserUtils.getInstance(), GeyserUtilsChannels.MAIN, GeyserUtils.getPacketManager().encodePacket(packet));
+    }
+
+    public static void sendFloatProperty(Player player, Entity entity, String identifier, Float value) {
+        EntityPropertyPacket<Float> packet = new EntityPropertyPacket<>();
+        packet.setEntityId(entity.getEntityId());
+        packet.setIdentifier(identifier);
+        packet.setValue(value);
+        player.sendPluginMessage(GeyserUtils.getInstance(), GeyserUtilsChannels.MAIN, GeyserUtils.getPacketManager().encodePacket(packet));
+    }
+
+    public static void sendIntProperty(Player player, Entity entity, String identifier, Integer value) {
+        EntityPropertyPacket<Integer> packet = new EntityPropertyPacket<>();
+        packet.setEntityId(entity.getEntityId());
+        packet.setIdentifier(identifier);
+        packet.setValue(value);
+        player.sendPluginMessage(GeyserUtils.getInstance(), GeyserUtilsChannels.MAIN, GeyserUtils.getPacketManager().encodePacket(packet));
+    }
 }