code: @ExceptionHandler(AbstractServerRtException.class)
      public ResponseEntity<ExceptionInfo> handleSpServerRtExceptions(final HttpServletRequest request,
              final Exception ex) {
          logRequest(request, ex);
          final ExceptionInfo response = createExceptionInfo(ex);
          final HttpStatus responseStatus;
          if (ex instanceof AbstractServerRtException) {
              responseStatus = getStatusOrDefault(((AbstractServerRtException) ex).getError());
          } else {
              responseStatus = DEFAULT_RESPONSE_STATUS;
          }
          return new ResponseEntity<>(response, responseStatus);
      }
docs: method for handling exception of type AbstractServerRtException. Called
  by the Spring-Framework for exception handling.
  
  @param request
  the Http request
  @param ex
  the exception which occurred
  
  @return the entity to be responded containing the exception information
  as entity.