Proguard Keep method in the same class

class Example implements PacketListenerClass {
    public Example() {
        Client client = new Client();
        client.registerPacketListener(this);
    }

    @PacketListener // This method must be in this class
    public void onPacketDisconnect(PacketDisconnect packetDisconnect) {
        // Code
    }

    @PacketListener // Same of onPacketDisconnect
    public void onPacketOther(PacketOther packetOther) {
        // Code
    }
}

Hi!, i need to keep method in the same class that implements PacketListenerClass, this method are invoked by reflection and annotated with @PacketListener , i tried with this configuration but didn't work

-keep class * implements some.package.PacketListenerClass