Configuring MessageTransformer for ActiveMQ/Stomp in SpringBoot - spring-boot

Question

I have a springboot project with ActiveMQ and Stomp.
I want every Message sent or received to run through a MessageTransformer, to do specific serialization/deserialization stuff.
The Stomp Message exchange with my WebApp works, but the installed MessageTransformer is never called.
Does anybody have an idea what could be wrong? Thank you much!
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.MessageTransformer;
import org.apache.activemq.broker.BrokerFactory;
import org.apache.activemq.broker.BrokerService;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.simp.config.MessageBrokerRegistry;
import org.springframework.web.socket.config.annotation.AbstractWebSocketMessageBrokerConfigurer;
import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
import org.springframework.web.socket.config.annotation.StompEndpointRegistry;
#Configuration
#EnableWebSocketMessageBroker
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
#Value("${stomp.port}") // 61616
int stompPort;
#Bean
public ActiveMQConnectionFactory activeMQConnectionFactory() {
ActiveMQConnectionFactory activeMQConnectionFactory =
new ActiveMQConnectionFactory("vm://localhost");
// Install Message Converter ## But does not work ##
MessageTransformer messageTransformer = new ClientMessageTransformer();
activeMQConnectionFactory.setTransformer(messageTransformer);
return activeMQConnectionFactory;
}
#Bean
public BrokerService brokerService() throws Exception {
BrokerService brokerService =
BrokerFactory.createBroker(String.format(
"broker:(stomp://localhost:%d)" +
"?persistent=false&useJmx=false&useShutdownHook=true",
stompPort));
return brokerService;
}