spring boot kotlin validation问题

背景

@ApiModelProperty(value = "markdown原始内容", required = true)
@NotBlank(message = "markdown内容不能为空")
var md: String? = "",

@ApiModelProperty(value = "markdown原始内容", required = true)
@field:NotBlank(message = "markdown内容不能为空")
var md: String? = "",

@ExceptionHandler(BindException::class)
@ResponseStatus(HttpStatus.BAD_REQUEST)
@ResponseBody
fun handle(e: BindException): R<Any> {
    val err = e.bindingResult.fieldErrors
    val msg = err[0].defaultMessage
    return R.fail(9005, msg ?: "未知错误")
}