Spring Validation Framework Resolving Error Codes

How do you wire Spring Validation Errors to error strings in messages.properties?

• My Validator throws a custom RuntimeException that wraps the spring Errors object.
• My @ControllerAdvice intercepts the exception and transforms the RuntimeException into a DTO object called WebExceptionMessage.
• The DTO WebExceptionMessage object has a List of custom WebValidationError objects that are transformations of the Spring Errors object.
• I have messages.properties in my classpath with keys that match the error codes in the Spring Validation Errors object.

How, when and where are the Spring Validation Errors agumented with the values found in messages.properties?

I read all about automagic wirings and tried them but whatever I do it doesn't work...

src/main/resources/messages.properties

field.required=Missing mandatory field.
field.numeric_only=Field must contain numbers only.
// more

MyValidator.java

@Component
public class MyValidator implements Validator{
  // code
  public void validate(Object target, Errors errors) {
    ValidationUtils.rejectIfEmpty(errors, "audit", "field.required");
    if(errors.hasErrors()){
      throw new MyRuntimeException(MyErrorCode.INVALID_REQUEST, "Failed Validator").errors(errors);
    }   
  }
}

WebExceptionHandler.java

@ControllerAdvice
public class WebExceptionHandler {
  @ExceptionHandler(value=MyRuntimeException.class)
  public ResponseEntity<WebExceptionMessage> myRuntimeException(MyRuntimeException e){
    WebExceptionMessage msg = new WebExceptionMessage();

    // code

    if(e.hasErrors()){
      List<WebValidationError> errors = new ArrayList<WebValidationError>();
      List<FieldError> fieldErrors = e.getErrors().getFieldErrors();
      for(FieldError err : fieldErrors){

        // =============================
        // I think somewhere over here I need to map the err.getCode()
        // to the value in messages.properties but isn't spring supposed 
        // to "magically" do that somehow and place the value in err.getDefaultMessage()
        //
        // I am probably completely off base here...please advise.
        // =============================

        errors.add(new WebValidationError(err.getCode(), err.getField(), err.getDefaultMessage()));


      }
      msg.setErrors(errors);
    }

    return new ResponseEntity<WebExceptionMessage>(msg, e.getErrorCode().getStatus());
  }
}

MyRuntimeException.java

public class MyRuntimeException extends RuntimeException {
  private org.springframework.validation.Errors errors;
  // code
  public MyRuntimeException errors(final Errors errors){
    this.errors = errors;
    return this;
  }  
}

WebExceptionMessage.java

public class WebExceptionMessage implements Serializable{
  // code
  private List<WebValidationError> errors;
}