Add default firework flight length in 1.20.5->1.20.3 (#3866)

common/src/main/java/com/viaversion/viaversion/protocols/v1_20_3to1_20_5/rewriter/BlockItemPacketRewriter1_20_5.java

@@ -387,6 +387,13 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
             return dataItem;
         }
 
+        if (dataConverter.backupInconvertibleData()) {
+            // In 1.20.6, some items have default values which are not written into the components
+            if (item.identifier() == 1105 && !data.contains(StructuredDataKey.FIREWORKS)) {
+                data.set(StructuredDataKey.FIREWORKS, new Fireworks(1, new FireworkExplosion[0]));
+            }
+        }
+
         for (final StructuredData<?> structuredData : data.data().values()) {
             dataConverter.writeToTag(connection, structuredData, tag);
         }

common/src/main/java/com/viaversion/viaversion/protocols/v1_20_3to1_20_5/rewriter/StructuredDataConverter.java

@@ -234,14 +234,16 @@ public final class StructuredDataConverter {
         });
         register(StructuredDataKey.FIREWORKS, (data, tag) -> {
             final CompoundTag fireworksTag = new CompoundTag();
-            fireworksTag.putInt("Flight", data.flightDuration());
+            fireworksTag.putByte("Flight", (byte) data.flightDuration());
             tag.put("Fireworks", fireworksTag);
 
-            final ListTag<CompoundTag> explosionsTag = new ListTag<>(CompoundTag.class);
-            for (final FireworkExplosion explosion : data.explosions()) {
-                explosionsTag.add(convertExplosion(explosion));
+            if (data.explosions().length > 0) {
+                final ListTag<CompoundTag> explosionsTag = new ListTag<>(CompoundTag.class);
+                for (final FireworkExplosion explosion : data.explosions()) {
+                    explosionsTag.add(convertExplosion(explosion));
+                }
+                fireworksTag.put("Explosions", explosionsTag);
             }
-            fireworksTag.put("Explosions", explosionsTag);
         });
         register(StructuredDataKey.FIREWORK_EXPLOSION, (data, tag) -> tag.put("Explosion", convertExplosion(data)));
         register(StructuredDataKey.PROFILE, (data, tag) -> {
@@ -871,6 +873,10 @@ public final class StructuredDataConverter {
         rewriters.put(key, c);
     }
 
+    public boolean backupInconvertibleData() {
+        return backupInconvertibleData;
+    }
+
     @FunctionalInterface
     interface SimpleDataConverter<T> {