What is the layout file for Magento_Sales LoadBlock controller

Question

Main question is:
What is the layout file for

\Magento\Sales\Controller\Adminhtml\Order\Create\LoadBlock

controller?

Here is some background why I needed that:
I am making custom module that will have similar functionality as Magento_Sales modules (pages where admin can create new order). I've copied all needed files form Magento_Sales module, and at the end I can't figure out what is layout for

\Magento\Sales\Controller\Adminhtml\Order\Create\LoadBlock

As you can see on github Link there is no layout file sales_order_create_loadblock.xml

In LoadBlock execute method
Link
there is some code for adding handle

foreach ($blocks as $block) {
  $resultPage->addHandle('sales_order_create_load_block_' . $block);
}

for each block, but I can't find where the main layout file is included.

Answer 1

I've walked via xdebug and figured out the basic layout functionality for this.

There is two layout handlers for this controller: default and sales_order_create_loadblock

When a result page is created

/** @var \Magento\Framework\View\Result\Page $resultPage */
$resultPage = $this->resultPageFactory->create();

only these two handlers are added. After that, for each block another handler is added, but that is obviously from the controller's code.

According to Magento's documentation if file

sales_order_create_loadblock.xml

doesn't exist, the controller will use

default.xml

(in this case file from admin theme,

/vendor/magento/theme-adminhtml-backend/Magento_Backend/layout/default.xml)

merged will all others default.xml files from active modules and themes).

So, the answer is not so simple for me, but now I understand how layout system works