Summary

javax.imageio.spi.ServiceRegistry.finalize() is removed.

Problem

Finalization is deprecated, but javax.imageio.spi.ServiceRegistry has a finalize() method.

Solution

• Remove the finalize() method.
• Document that if a ServiceRegistry is no longer needed, the application should call ServiceRegistry.deregisterAll()
• Remove from other methods javadoc, text related to the finalization behaviour
• Not related, but also update the class doc to remove obsolete reference to runtime permissions.
• Update the implementation and specification of javax.imageio.spi.IIORegistry.getDefaultInstance() so that it is now a singleton in all cases, and so never will be collected.

Specification

javax/imageio/spi/ServiceRegistry.java class doc

* <p> An application may customize the contents of a registry as it
- * sees fit, so long as it has the appropriate runtime permission.
+ * sees fit.

finalize method removal

-    /**
-     * Finalizes this object prior to garbage collection.  The
-     * {@code deregisterAll} method is called to deregister all
-     * currently registered service providers.  This method should not
-     * be called from application code.
-     *
-     * @throws Throwable if an error occurs during superclass
-     * finalization.
-     *
-     * @deprecated Finalization has been deprecated for removal.  See
-     * {@link java.lang.Object#finalize} for background information and details
-     * about migration options.
-     */
-    @Deprecated(since="9", forRemoval=true)
-    @SuppressWarnings("removal")
-    public void finalize() throws Throwable 

public void registerServiceProvider(Object provider)
      * {@code onDeregistration} method will be called each time
-     * it is deregistered from a category or when the registry is
-     * finalized.
+     * it is deregistered from a category.

public void registerServiceProviders(Iterator<?> providers) {
      * {@code onDeregistration} method will be called each time
-     * it is deregistered from a category or when the registry is
-     * finalized.
+     * it is deregistered from a category.

     public void deregisterAll() 
+     * If an application creates a new {@code ServiceRegistry} instance and registers providers,
+     * and at some point no longer needs the instance, it should call this method to ensure
+     * that all providers which are instances of {@link RegisterableService}
+     * receive a {@link RegisterableService#onDeregistration(ServiceRegistry, Class<?>)} call back,
+     * before allowing the instance to be garbage collected.

javax/imageio/spi/IIORegistry

     /**
      * Returns the default {@code IIORegistry} instance used by
      * the Image I/O API.  This instance should be used for all
      * registry functions.
-     *
-     * <p> Each {@code ThreadGroup} will receive its own instance.
-     *
-     * @return the default registry for the current
-     * {@code ThreadGroup}.
+     * @return the default registry for the Image I/O API
      */
     public static IIORegistry getDefaultInstance()