Let's create a bean to define the structure of our custom exception message. 

We have created the following simple exception response bean with an auto-populated timestamp and a few additional properties, namely messages and details:

    public class ExceptionResponse {

      private Date timestamp = new Date();
      private String message;
      private String details;

      public ExceptionResponse(String message, String details) {
        super();
        this.message = message;
        this.details = details;
       }

      public Date getTimestamp() {
        return timestamp;
      }

      public String getMessage() {
        return message;
      }

      public String getDetails() {
        return details;
      }

   }

When TodoNotFoundException is thrown, we want to return a response using the ExceptionResponse bean.