We will create a simple WelcomeBean POJO (short for Plain Old Java Object) with a member field called message and one argument constructor, as shown in the following line of code:

data class WelcomeBean(val message: String = "")

The corresponding Java class is listed as follows:

    public class WelcomeBean {

      private String message;

      public WelcomeBean(String message) {
        super();
        this.message = message;
      }

      public String getMessage() {
        return message;
     }
   }

Kotlin automatically adds constructors and other utility methods to the data classes.

In the previous method, we returned a string. Let's create a method that returns a proper JSON response. Take a look at the following method:

    @GetMapping("/welcome-with-object")
    fun welcomeWithObject() = WelcomeBean("Hello World")

The method returns a simple WelcomeBean initialized with a "Hello World" message.