How to make Rasa bot utter a response using Java

Question

I am trying to create a rasa bot using Java in Springboot application. One of the use cases is that if a user is able to log in successfully by giving a command like “login:username password” to the rasa chatbot then the bot should respond “Login successful” else “Invalid credentials”. To verify the credentials, I am calling an API in another service that returns if the login is successful or not. How do I make the bot respond according to the situation? Is there any API that I can use to make the bot utter a particular response? As far as I can see, this API has been deprecated. Do we have an alternative? https://rasa.com/docs/rasa/pages/http-api#operation/executeConversationAction

if(feignResponse.getStatusCode().value() == 200) {
    System.out.println("YES");
    rasaClient.makeBotUtterance("Login successful");
 }
  else{ 
    System.out.println("NOPE");
    rasaClient.makeBotUtterance("Invalid credentials");
            }

Which Rasa http api can I use inside makeBotUtterance?