Spring Validator Not Providing Message to Client

I'm currently developing a Spring RESTful service and am using the validation annotation to ensure parameters within the object of the body of the request are present. However, for some reason the Spring validation does not appear to, by default, provide the client user with ANY information on why their request could have been invalid

Data Object class:

....
    @Min(10000000000L)
    @Max(19999999999L)
    private long id;
    
    private boolean restricted;
.....

Controller:

@PostMapping("/userRestriction")
    public ResponseEntity<String> userRestriction(
            @Valid @RequestBody(required = true) User user) {

Post:

{
	"id":"A",
	"restricted":false
}

Result:

{
    "timestamp": "2020-07-23T14:20:57.273+00:00",
    "status": 400,
    "error": "Bad Request",
    "message": "",
    "path": "/userRestriction"
}

Logs:

2020-07-23 09:20:57.271  WARN 28035 --- [nio-8080-exec-5] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot deserialize value of type `long` from String "A": not a valid Long value; nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type `long` from String "A": not a valid Long value
 at [Source: (PushbackInputStream); line: 2, column: 11] (through reference chain: myPackage.dataObjects.User["id"])]

I was hoping that Spring would be able to at least provide the exception in the error message to get me by through a Minimum Viable Product iteration, so that way while it may be obtuse, a client can still ultimately understand what they did wrong, and I could add custom error handling later, but this doesn't seem to be the case?

If not, what are the methods I'd need to implement in a error/exception handler class to correctly handle validator errors?

Thanks

You can add the following class BindingResult bindingResult in the parameters of userRestriction()

@PostMapping("/userRestriction")
public ResponseEntity<String> userRestriction(
        @Valid @RequestBody(required = true) User user, BindingResult bindingResult)

Then inside your method you can do something like

if (bindingResult.hasErrors()) {
    //Whatever you want to do
}

BindingResult provides acces and handling to the validation of your Bean associated with @Valid

More information about how to handle it can be found here: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/validation/BindingResult.html

I would suggest you use the method getAllErrors() which will return a list of all the errors given by the validation.
You can also implement a custom exception to be thrown when these errors exist.

Let me give you a code snippet for implementing a handler exception with Spring

@ControllerAdvice
public class RestResponseEntityExceptionHandler 
 extends ResponseEntityExceptionHandler {

@ExceptionHandler(value 
  = { IllegalArgumentException.class, IllegalStateException.class })
protected ResponseEntity<Object> handleConflict(
  RuntimeException ex, WebRequest request) {
    String bodyOfResponse = "This should be application specific";
    return handleExceptionInternal(ex, bodyOfResponse, 
      new HttpHeaders(), HttpStatus.CONFLICT, request);
}
}

This is the most useful I have used so far, you just need to adapt it to your needs. You can find further information following this tutorial: https://www.baeldung.com/exception-handling-for-rest-with-spring