created new custom export Entity Type in magento 2

I have created custom Entity Type in Magento 2 but not showing Entity Attributes list after selecting entity type.

Here is my code :-

<?php

namespace TestVendorModelExport;

/**
 * Class Constructs
 */
class Constructs extends MagentoImportExportModelExportAbstractEntity
{
    /**
     * Permanent column names
     */
    const PATTERN_ID = 'pattern_id';
    const NAME = 'name';
    const SKU_PATTERN = 'sku_pattern';
    const SKU_LIST = 'sku_list';
    const STATUS = 'status';
    const STORE_ID = 'store_ids';

    /**
     * Permanent entity columns
     *
     * @var string[]
     */
    protected $_permanentAttributes = [
        self::PATTERN_ID,
        self::NAME,
        self::SKU_PATTERN,
        self::SKU_LIST,
        self::STATUS,
        self::STORE_ID,
    ];

    public function export()
    {
        // TODO: Implement export() method.
    }

    public function exportItem($item)
    {
        // TODO: Implement exportItem() method.
    }

    public function getEntityTypeCode()
    {
        return  'constructs';
    }

    protected function _getHeaderColumns()
    {
        return $this->_permanentAttributes;
    }

    protected function _getEntityCollection()
    {
        // TODO: Implement _getEntityCollection() method.
    }
}

Also i have click on continue button showing this error :- Please correct the data sent value.