@Test
public void handleAck() throws ChannelNotFoundException {
final String channelId_1 = UUID.randomUUID().toString();
final String channelId_2 = UUID.randomUUID().toString();
final String uaid = UUIDUtil.newUAID();
final RegisterResponse registerResponse1 = server.handleRegister(new RegisterMessageImpl(channelId_1), uaid);
final String endpointToken1 = extractEndpointToken(registerResponse1.getPushEndpoint());
final RegisterResponse registerResponse2 = server.handleRegister(new RegisterMessageImpl(channelId_2), uaid);
final String endpointToken2 = extractEndpointToken(registerResponse2.getPushEndpoint());
server.handleNotification(endpointToken1, "version=10");
server.handleNotification(endpointToken2, "version=23");
final Ack ackChannel_1 = new AckImpl(channelId_1, 10L);