Kotlin Swagger UI以非分解形式发送表单参数

我不明白为什么“columns”和“documentid”参数被swagger ui作为逗号分隔的值发送，而不是作为默认的分解键=val1&key=val2形式发送

定义如下：

        RouterOperation(
            path = "$BASE_PATH/loss/excel",
            beanClass = ExcelExportHandler::class,
            beanMethod = "export",
            method = [POST],
            operation = Operation(
                operationId = "excelExport",
                security = [
                    SecurityRequirement(name = "Authorization")
                ],
                requestBody = RequestBody(
                    required = true,
                    description = "form data",
                    content = [
                        Content(
                            mediaType = APPLICATION_FORM_URLENCODED_VALUE,
                            schema = Schema(implementation = ExcelExportRequest::class),
                            encoding = [
                                Encoding(name = "columns", explode = true),
                                Encoding(name = "documentIds", explode = true)
                            ]
                        )
                    ],

                ),
                responses = [
                    ApiResponse(
                        content = [
                            Content(
                                mediaType = APPLICATION_OCTET_STREAM_VALUE
                            )
                        ]
                    ),
                    ApiResponse(
                        responseCode = "200"
                    )
                ]
            )
        )

请求：

internal class ExcelExportRequest {
    @Schema(name = "columns", required = true)
    var columns: List<String>? = null

    @Schema(name = "documentIds", required = true)
    var documentIds: List<String>? = null
}

内部类请求{
@架构（name=“columns”，required=true）
变量列：列表？=null
@架构（name=“documentIds”，required=true）
var documentIds:列表？=null
}

使用swagger-2.1.2（OpenAPI v3）