private ErrorResponse toErrorResponse(ValidationException ve) {
        if (ve instanceof ConstraintViolationException) {
            return constraintViolationExceptionToErrorResponse((ConstraintViolationException) ve);
        } else {
            ErrorResponse result = new ErrorResponse();
            result.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());
            result.setMessage(ve.getMessage());
            result.setInstance(host);
            return result;
        }
    }
This class converts Hibernate {@link ValidationException} into http response.
rest/src/main/java/com/netflix/conductor/rest/controllers/ValidationExceptionMapper.java