src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedLongSynchronizer.java

@@ -63,10 +63,15 @@
     extends AbstractOwnableSynchronizer
     implements java.io.Serializable {
 
     private static final long serialVersionUID = 7373984972572414692L;
 
+    /**
+     * Constructor for subclasses to call.
+     */
+    public AbstractQueuedLongSynchronizer() {}
+
     /*
      * To keep sources in sync, the remainder of this source file is
      * exactly cloned from AbstractQueuedSynchronizer, replacing class
      * name and changing ints related with sync state to longs. Please
      * keep it that way.