client.invoke(CALLBACK_TEST);
assertEquals(1, callbackHandler.counter);
log.info("callback handler is installed");
// Verify that "callbackTimeout" is used correctly.
SocketServerInvoker serverInvoker = (SocketServerInvoker) connector.getServerInvoker();
Field field = ServerInvoker.class.getDeclaredField("callbackHandlers");
field.setAccessible(true);
Map callbackHandlers = (Map) field.get(serverInvoker);
assertEquals(1, callbackHandlers.size());
ServerInvokerCallbackHandler serverInvokerCallbackHandler;