public boolean destroy() {
        if (!destroyed.getAndSet(true)) {
            close();
            return true;
        }
        return false;
    }
Sets the destroyed flag to true. The very first time this method is called, it cleans up all its dependencies.
Even if you retain a reference to this object, all of its content is allowed to be garbage collected.

@return True if content existed and was destroyed.
messagebus/src/main/java/com/yahoo/messagebus/DestinationSession.java