Clean-up Javac Overrides Warnings In javax/management/NotificationBroadcasterSupport.java

When building jdk source code, the build log shows the following javac overrides warnings from NotificationBroadcasterSupport.java file.

jdk/src/share/classes/javax/management/NotificationBroadcasterSupport.java:278: warning: [overrides] Class ListenerInfo overrides equals, but neither it nor any superclass overrides hashCode method
    private static class ListenerInfo {
                   ^

/jdk/src/share/classes/javax/management/NotificationBroadcasterSupport.java:303: warning: [overrides] Class WildcardListenerInfo overrides equals, but neither it nor any superclass overrides hashCode method
    private static class WildcardListenerInfo extends ListenerInfo {
                   ^