Context: How does \Magento\Sales\Model\ResourceModel\Order\Relation::processRelation() work?
\Magento\Sales\Model\ResourceModel\Order\Relation::processRelation()
Details: How does an order address saving work?
Details: How does \Magento\Sales\Model\ResourceModel\Attribute::saveAttribute() work?
\Magento\Sales\Model\ResourceModel\Attribute::saveAttribute()