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

*** 78,88 ****
          if (observer == null) {
              return null;
          }
  
          synchronized (ObserverCache.INSTANCE) {
!             ImageObserver o = (ImageObserver) ObserverCache.INSTANCE.get(image);
  
              if (o == null) {
  
                  o = (Image resolutionVariant, int flags,
                          int x, int y, int width, int height) -> {
--- 78,88 ----
          if (observer == null) {
              return null;
          }
  
          synchronized (ObserverCache.INSTANCE) {
!             ImageObserver o = (ImageObserver) ObserverCache.INSTANCE.get(observer);
  
              if (o == null) {
  
                  o = (Image resolutionVariant, int flags,
                          int x, int y, int width, int height) -> {
*** 107,117 ****
  
                              return observer.imageUpdate(
                                      image, flags, x, y, width, height);
                          };
  
!                 ObserverCache.INSTANCE.put(image, o);
              }
              return o;
          }
      }
  }
--- 107,117 ----
  
                              return observer.imageUpdate(
                                      image, flags, x, y, width, height);
                          };
  
!                 ObserverCache.INSTANCE.put(observer, o);
              }
              return o;
          }
      }
  }