better network structure

app/src/main/java/network/protocol/packets/KeepAlivePacket.java

@@ -0,0 +1,26 @@
+package network.protocol.packets;
+
+import network.protocol.Packet;
+import network.protocol.PacketVisitor;
+import network.protocol.Packets;
+
+public class KeepAlivePacket extends Packet {
+
+	static private final long serialVersionUID = Packets.KeepAlive.ordinal();
+
+	private final long keepAliveId;
+
+	public KeepAlivePacket(long keepAliveId) {
+		this.keepAliveId = keepAliveId;
+	}
+
+	public long getKeepAliveId() {
+		return keepAliveId;
+	}
+
+	@Override
+	public void accept(PacketVisitor packetVisitor) {
+		packetVisitor.visitPacket(this);
+	}
+
+}