I am wondering if and how it is possible to either overwrite or plug in to an observer method?
I tried to set a preference in /etc/frontend/di.xml:
<preference for="Magento\Quote\Observer\Frontend\Quote\Address\CollectTotalsObserver"
type="Vendor\Module\Observer\Frontend\Quote\Address\CollectTotalsObserver"/>
If I add a logging to the original class and to my custom one, I can see that still the original class is executed, but not my overwritten one.
I then tried to add code with a plugin in same di.xml:
<type name="Magento\Quote\Observer\Frontend\Quote\Address\CollectTotalsObserver">
<plugin disabled="false" name="Vendor_Module_Plugin_Magento_Quote_Observer_Frontend_Quote_Address_CollectTotalsObserver" sortOrder="10"
type="Vendor\Module\Plugin\Magento\Quote\Observer\Frontend\Quote\Address\CollectTotalsObserver"/>
</type>
But still no logging output. Of course I cleared cache, run setup:upgrade and setup:di:compile, but it just does not work. I am sure that all files are in the correct place and classes named correctly.
Can someone explain this or give me any hint?