BundleImportExport is missing `selection_can_change_qty`

[barryvdh]

Preconditions

1. Magento 2.1.6

Steps to reproduce

1. Create a Bundle product with options.
2. Export the product, no information about selection_can_change_qty
3. Import, no possibility to set selection_can_change_qty

Expected result

selection_can_change_qty is exported and imported correctly

Actual result

selection_can_change_qty is always true/1

Suggested solution

It seems that while importing, the value is hardcoded: https://github.com/magento/magento2/blob/2.1.6/app/code/Magento/BundleImportExport/Model/Import/Product/Type/Bundle.php#L310

I suggest a parameter can_change_qty will be added, while keeping the default on 1 to preserve BC.

'selection_can_change_qty' => (isset($selection['can_change_qty'])) ? ($selection['can_change_qty'] ? 1 : 0) : 1,

The value should also be added to the export of a bundle, to keep import <-> export in sync.

[IlnitskiyArtem]

@barryvdh, Thanks for reporting this issue. We've created internal ticket MAGETWO-70390 to address this issue.