8009038: Improve JMX notification support

Summary: Disallowing access to mutable shared arrays
Reviewed-by: dfuchs, mchung, skoivu

src/share/classes/javax/management/StandardEmitterMBean.java

@@ -64,6 +64,9 @@ package javax.management;
 public class StandardEmitterMBean extends StandardMBean
         implements NotificationEmitter {
 
+    private static final MBeanNotificationInfo[] NO_NOTIFICATION_INFO =
+        new MBeanNotificationInfo[0];
+
     private final NotificationEmitter emitter;
     private final MBeanNotificationInfo[] notificationInfo;
 
@@ -99,11 +102,7 @@ public class StandardEmitterMBean extends StandardMBean
      */
     public <T> StandardEmitterMBean(T implementation, Class<T> mbeanInterface,
                                     NotificationEmitter emitter) {
-        super(implementation, mbeanInterface, false);
-        if (emitter == null)
-            throw new IllegalArgumentException("Null emitter");
-        this.emitter = emitter;
-        this.notificationInfo = emitter.getNotificationInfo();
+        this(implementation, mbeanInterface, false, emitter);
     }
 
     /**
@@ -148,7 +147,12 @@ public class StandardEmitterMBean extends StandardMBean
         if (emitter == null)
             throw new IllegalArgumentException("Null emitter");
         this.emitter = emitter;
-        this.notificationInfo = emitter.getNotificationInfo();
+        MBeanNotificationInfo[] infos = emitter.getNotificationInfo();
+        if (infos == null || infos.length == 0) {
+            this.notificationInfo = NO_NOTIFICATION_INFO;
+        } else {
+            this.notificationInfo = infos.clone();
+        }
     }
 
     /**
@@ -184,11 +188,7 @@ public class StandardEmitterMBean extends StandardMBean
      */
     protected StandardEmitterMBean(Class<?> mbeanInterface,
                                    NotificationEmitter emitter) {
-        super(mbeanInterface, false);
-        if (emitter == null)
-            throw new IllegalArgumentException("Null emitter");
-        this.emitter = emitter;
-        this.notificationInfo = emitter.getNotificationInfo();
+        this(mbeanInterface, false, emitter);
     }
 
     /**
@@ -231,7 +231,12 @@ public class StandardEmitterMBean extends StandardMBean
         if (emitter == null)
             throw new IllegalArgumentException("Null emitter");
         this.emitter = emitter;
-        this.notificationInfo = emitter.getNotificationInfo();
+        MBeanNotificationInfo[] infos = emitter.getNotificationInfo();
+        if (infos == null || infos.length == 0) {
+            this.notificationInfo = NO_NOTIFICATION_INFO;
+        } else {
+            this.notificationInfo = infos.clone();
+        }
     }
 
     public void removeNotificationListener(NotificationListener listener)
@@ -253,7 +258,11 @@ public class StandardEmitterMBean extends StandardMBean
     }
 
     public MBeanNotificationInfo[] getNotificationInfo() {
+        if (notificationInfo.length == 0) {
             return notificationInfo;
+        } else {
+            return notificationInfo.clone();
+        }
     }
 
     /**