v1.0.9: Fix error parent product not show Pre Order button when all child products are pre order

QUESTION:

We use module PreOrder version 1.0.9 for my Magento 2.2.

However, there is an issue that I notice that when all the child products are pre-order, parent product doesn't show the Pre-Order button.

If there any way to fix this error? 

ANSWER: 

To fix this error, please edit files as below:

+ app/code/Bss/CustomizePreOrder/Helper/ProductData.php

• 
  
• + app/code/Bss/CustomizePreOrder/Plugin/CategoryCheck.php

Or download the attached files below and overwrite the current files on your site.

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