src/java.desktop/share/classes/sun/awt/image/MultiResolutionToolkitImage.java

@@ -78,11 +78,11 @@
         if (observer == null) {
             return null;
         }
 
         synchronized (ObserverCache.INSTANCE) {
-            ImageObserver o = (ImageObserver) ObserverCache.INSTANCE.get(image);
+            ImageObserver o = (ImageObserver) ObserverCache.INSTANCE.get(observer);
 
             if (o == null) {
 
                 o = (Image resolutionVariant, int flags,
                         int x, int y, int width, int height) -> {

@@ -107,11 +107,11 @@
 
                             return observer.imageUpdate(
                                     image, flags, x, y, width, height);
                         };
 
-                ObserverCache.INSTANCE.put(image, o);
+                ObserverCache.INSTANCE.put(observer, o);
             }
             return o;
         }
     }
 }