Use an ArrayLIst for adjacent objects for sharing finalizers.

Author: aardvark179

src/main/java/org/truffleruby/core/FinalizerReference.java

@@ -49,7 +49,7 @@ FinalizationService.Finalizer getFirstFinalizer() {
         return finalizers.pollFirst();
     }
 
-    void collectRoots(Collection<Object> roots) {
+    public void collectRoots(Collection<Object> roots) {
         for (FinalizationService.Finalizer finalizer : finalizers) {
             final RubyDynamicObject root = finalizer.getRoot();
             if (root != null) {

src/main/java/org/truffleruby/language/objects/shared/WriteBarrierNode.java

@@ -15,7 +15,7 @@
 import org.truffleruby.language.RubyDynamicObject;
 import org.truffleruby.language.objects.ShapeCachingGuards;
 
-import java.util.HashSet;
+import java.util.ArrayList;
 
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.dsl.Cached;
@@ -81,8 +81,8 @@ protected void writeBarrierUncached(RubyDynamicObject value) {
     @Specialization
     @TruffleBoundary
     protected void writeBarrierFinalizer(FinalizerReference ref) {
-        HashSet<Object> roots = new HashSet<>();
-        ref.getAdjacentObjects(roots);
+        ArrayList<Object> roots = new ArrayList<>();
+        ref.collectRoots(roots);
         for (var root : roots) {
             SharedObjects.writeBarrier(getLanguage(), root);
         }