Fix some packet entity data crap, fixes #61

TerminatorPlus-Plugin/src/main/java/net/nuggetmc/tplus/utils/NMSUtils.java

@@ -0,0 +1,42 @@
+package net.nuggetmc.tplus.utils;
+
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
+import net.minecraft.network.syncher.SynchedEntityData;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.util.ArrayList;
+import java.util.List;
+
+public class NMSUtils {
+    private static String itemsByIdFieldName;
+    static {
+        // find a private final field in SynchedEntityData that is an Int2ObjectMap<SynchedEntityData.DataItem>
+        Class<SynchedEntityData> clazz = SynchedEntityData.class;
+        Field[] fields = clazz.getDeclaredFields();
+        for (Field field : fields) {
+            if (field.getType().equals(Int2ObjectMap.class) && Modifier.isPrivate(field.getModifiers()) && Modifier.isFinal(field.getModifiers())) {
+                itemsByIdFieldName = field.getName();
+                break;
+            }
+        }
+        if (itemsByIdFieldName == null) {
+            throw new RuntimeException("Could not find itemsById field in SynchedEntityData");
+        }
+    }
+    public static List<SynchedEntityData.DataValue<?>> getEntityData(SynchedEntityData synchedEntityData) {
+        Int2ObjectMap<SynchedEntityData.DataItem> map = null;
+        try {
+            Field field = synchedEntityData.getClass().getDeclaredField(itemsByIdFieldName);
+            field.setAccessible(true);
+            map = (Int2ObjectMap<SynchedEntityData.DataItem>) field.get(synchedEntityData);
+        } catch (NoSuchFieldException | IllegalAccessException e) {
+            throw new RuntimeException(e);
+        }
+        List<SynchedEntityData.DataValue<?>> entityData = new ArrayList<>();
+        for (SynchedEntityData.DataItem<?> dataItem : map.values()) {
+            entityData.add(dataItem .value());
+        }
+        return entityData;
+    }
+}